code golf - Reversed Multiple Pair - Code Golf Stack Exchange

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4.36 0 8 3.64 8 8 0 4.36-3.64 8-8 8Zm0-2c3.27 0 6-2.73 6-6s-2.73-6-6-6-6 2.73-6 6 2.73 6 6 6ZM8 5h1.01L9 9.36l3.22 2.1-.6.93L8 10V5Z"/></svg> </div> <div class="flex--item wmn0 fl1 lh-lg"> <div class="flex--item fl1 lh-lg"> <b>The <a href="https://web.archive.org/web/20220202015155/https://codegolf.stackexchange.com/help/bounty">bounty</a> expires <span title="2022-02-08 17:10:56Z">in 7 days</span></b>. Answers to this question are eligible for a <span class="s-badge__bounty d-inline px4 py2 ba bc-transparent bar-sm fs-caption va-middle">+50</span> reputation bounty. <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/16766/dlosc">DLosc</a> wants to <b>reward an existing answer</b>: <blockquote> <div>For <a href="https://web.archive.org/web/20220202015155/https://codegolf.stackexchange.com/a/242142/16766">Razetime's second tinylisp answer</a> while tinylisp is <a href="https://web.archive.org/web/20220202015155/https://codegolf.meta.stackexchange.com/q/24402/16766">Language of the Month</a>.</div> </blockquote> </div> </div> </div> </div> </aside> </div> <h1>Intro</h1> <p>Two numbers are a <em>reversed multiple pair</em> if they satisfy the following property:</p> <p><span class="math-container">$$ a\times b = reversed( (a-1)\times b ) $$</span></p> <p>Here, <span class="math-container">\$reversed()\$</span> means to reverse the digits of a number (e. g <code>123</code> becomes <code>321</code>.)</p> <h1>Example</h1> <p><span class="math-container">$$ a=6, b=9, 6\times9=54,5\times9=45 $$</span></p> <p>As you can see, <span class="math-container">\$45\$</span> is the reversed version of <span class="math-container">\$54\$</span>.</p> <h1>Task</h1> <p>Given two integers, <span class="math-container">\$a\$</span> and <span class="math-container">\$b\$</span>, output if these two numbers is a reversed multiple pair.</p> <h1>Test Cases</h1> <pre><code>6 9 => True 4 5 => False 3 2178 => True 34 2079 => True 7 8 => False 600 100 => False 46 1089 => True 817 503 => False 6 9009 => True 321 81 => False 10 1089 => False </code></pre> <p>Shortest code wins!</p> </div> <div class="mt24 mb12"> <div class="post-taglist d-flex gs4 gsy fd-column"> <div class="d-flex ps-relative fw-wrap"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/questions/tagged/code-golf" class="post-tag" title="show questions tagged 'code-golf'" 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class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/105116/bgil-midol"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/NRwfk.png?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/105116/bgil-midol">Bgil Midol</a><span class="d-none" itemprop="name">Bgil Midol</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">1,665</span><span title="3 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">3</span></span><span class="v-visible-sr">3 silver badges</span><span title="23 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">23</span></span><span class="v-visible-sr">23 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount">8</span> <div class="post-layout--right js-post-comments-component"> <div id="comments-241992" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="241992" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="3" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-545394" class="comment js-comment " data-comment-id="545394" data-comment-owner-id="97916" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">Suggest test case: <code>321 81 => False</code>. An answer checking <code>b</code> for divisibility with 9 will pass all existing test cases but not this one.</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/97916/chunes" title="6,030 reputation" class="comment-user">chunes</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-29 21:43:38Z, License: CC BY-SA 4.0" class="relativetime-clean">Jan 29 at 21:43</span></span> <span title="this comment was edited 1 time"> <svg aria-hidden="true" class="va-text-bottom o50 svg-icon iconPencilSm" width="14" height="14" viewbox="0 0 14 14"><path d="m11.1 1.71 1.13 1.12c.2.2.2.51 0 .71L11.1 4.7 9.21 2.86l1.17-1.15c.2-.2.51-.2.71 0ZM2 10.12l6.37-6.43 1.88 1.88L3.88 12H2v-1.88Z"/></svg> </span> </div> </div> </li> <li id="comment-545424" class="comment js-comment " data-comment-id="545424" data-comment-owner-id="44718" data-comment-score="2"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">2</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">Is <code>10 1089</code> truthy or falsy? Currently, different answers don't agree on this testcase.</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/44718/tsh" title="26,720 reputation" class="comment-user">tsh</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 02:55:30Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> <span title="this comment was edited 2 times"> <svg aria-hidden="true" class="va-text-bottom o50 svg-icon iconPencilSm" width="14" height="14" viewbox="0 0 14 14"><path d="m11.1 1.71 1.13 1.12c.2.2.2.51 0 .71L11.1 4.7 9.21 2.86l1.17-1.15c.2-.2.51-.2.71 0ZM2 10.12l6.37-6.43 1.88 1.88L3.88 12H2v-1.88Z"/></svg> </span> </div> </div> </li> <li id="comment-545439" class="comment js-comment " data-comment-id="545439" data-comment-owner-id="44718" data-comment-score="2"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">2</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">May I assume inputs are positive? Or what is expected output for <code>-5 9</code>?</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/44718/tsh" title="26,720 reputation" class="comment-user">tsh</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 06:53:15Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> </div> </div> </li> <li id="comment-545462" class="comment js-comment " data-comment-id="545462" data-comment-owner-id="44718" data-comment-score="1"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">1</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">Shouldn’t 10 1089 be false?</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/44718/tsh" title="26,720 reputation" class="comment-user">tsh</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 13:03:06Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> </div> </div> </li> <li id="comment-545466" class="comment js-comment " data-comment-id="545466" data-comment-owner-id="44718" data-comment-score="3"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">3</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">reverse(9*1089)=reverse(9801)=1089≠10890=10*1089</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/44718/tsh" title="26,720 reputation" class="comment-user">tsh</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 14:22:02Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> <span title="this comment was edited 1 time"> <svg aria-hidden="true" class="va-text-bottom o50 svg-icon iconPencilSm" width="14" height="14" viewbox="0 0 14 14"><path d="m11.1 1.71 1.13 1.12c.2.2.2.51 0 .71L11.1 4.7 9.21 2.86l1.17-1.15c.2-.2.51-.2.71 0ZM2 10.12l6.37-6.43 1.88 1.88L3.88 12H2v-1.88Z"/></svg> </span> </div> </div> </li> </ul> </div> <div id="comments-link-241992" data-rep="50" data-anon="true"> <a class="js-add-link comments-link dno" title="Use comments to ask for more information or suggest improvements. Avoid answering questions in comments." href="#" role="button"></a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link " title="Expand to show all comments on this post" href="#" onclick="" role="button">Show <b>3</b> more comments</a> </div> </div> </div> </div> <div id="answers"> <a name="tab-top"></a> <div id="answers-header"> <div class="answers-subheader d-flex ai-center mb8"> <div class="flex--item fl1"> <h2 class="mb0" data-answercount="26"> 26 Answers <span style="display:none;" itemprop="answerCount">26</span> </h2> </div> <div class="flex--item"> <div class=" d-flex s-btn-group js-filter-btn"> <a class="flex--item s-btn s-btn__muted s-btn__outlined" href="/web/20220202015155/https://codegolf.stackexchange.com/questions/241992/reversed-multiple-pair?answertab=active#tab-top" data-nav-xhref="" title="Answers with the latest activity first" data-value="active" data-shortcut="A"> Active</a> <a class="flex--item s-btn s-btn__muted s-btn__outlined" href="/web/20220202015155/https://codegolf.stackexchange.com/questions/241992/reversed-multiple-pair?answertab=oldest#tab-top" data-nav-xhref="" title="Answers in the order they were provided" data-value="oldest" data-shortcut="O"> Oldest</a> <a class="youarehere is-selected flex--item s-btn s-btn__muted s-btn__outlined" href="/web/20220202015155/https://codegolf.stackexchange.com/questions/241992/reversed-multiple-pair?answertab=votes#tab-top" data-nav-xhref="" title="Answers with the highest score first" data-value="votes" data-shortcut="V"> Score</a> </div> </div> </div> </div> <a name="242009"></a> <div id="answer-242009" class="answer js-answer" data-answerid="242009" data-score="9" data-position-on-page="1" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242009"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="9"> 9 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242009/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/JCumin/Brachylog" rel="noreferrer">Brachylog</a>, 8 bytes</h1> <pre><code>-₁ʰ×↔~×? </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##SypKTM6ozMlPN/r/X/dRU@OpDYenP2qbUnd4uv3//9EmZjqGBhaWsf8B" rel="noreferrer" title="Brachylog – Try It Online">Try it online!</a></p> <h3>Explanation</h3> <pre><code> Input = [A, B] -₁ʰ Compute [A-1, B] × Compute (A-1) × B ↔ Reverse digits ~×? It can be unmultiplied into [A,B] </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T00:16:28"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242009"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242009" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242009/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242009" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-30 00:16:28Z" class="relativetime">Jan 30 at 0:16</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/41723/fatalize"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/zTCss.png?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/41723/fatalize">Fatalize</a><span class="d-none" itemprop="name">Fatalize</span> <div class="-flair"> <span class="reputation-score" title="reputation score 34,784" dir="ltr">34.8k</span><span title="4 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">4</span></span><span class="v-visible-sr">4 gold badges</span><span title="57 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">57</span></span><span class="v-visible-sr">57 silver badges</span><span title="144 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">144</span></span><span class="v-visible-sr">144 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242009" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242009" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242009" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <div class="js-zone-container zone-container-main"> <div id="dfp-mlb" class="everyonelovesstackoverflow everyoneloves__mid-leaderboard everyoneloves__leaderboard"></div> <div class="js-report-ad-button-container " style="width: 728px"></div> </div> <a name="241994"></a> <div id="answer-241994" class="answer js-answer" data-answerid="241994" data-score="6" data-position-on-page="2" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="241994"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="6"> 6 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/241994/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/DennisMitchell/jellylanguage" rel="noreferrer">Jelly</a>, 9 bytes</h1> <pre><code>,’$×DU⁼¥/ </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://jht.hyper-neutrino.xyz/tio#WyIiLCIs4oCZJMOXRFXigbzCpS8iLCIiLCIiLFsiMzQiLCIyMDc5Il1d" rel="noreferrer">Try It Online!</a></p> <pre><code>,’$×DU⁼¥/ Main Link; dyad accepting a, b ,’$ pair: [a, a - 1] × multiply: [ab, (a - 1)b] D to digit list / reduce between the two: U is the reverse of the former ⁼ equal to the latter? </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T20:45:09"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="241994"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/241994" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/241994/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-241994" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-29 20:45:09Z" class="relativetime">Jan 29 at 20:45</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/68942/hyper-neutrino"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/f6663ff2d61581b26bd021b3ce6b6376?s=64&d=identicon&r=PG" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/68942/hyper-neutrino">hyper-neutrino</a><span class="mod-flair mtn2" title="Moderator">♦</span><span class="d-none" itemprop="name">hyper-neutrino</span> <div class="-flair"> <span class="reputation-score" title="reputation score 41,012" dir="ltr">41k</span><span title="5 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">5</span></span><span class="v-visible-sr">5 gold badges</span><span title="61 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">61</span></span><span class="v-visible-sr">61 silver badges</span><span title="212 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">212</span></span><span class="v-visible-sr">212 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-241994" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="241994" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-241994" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. 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class="lang-python prettyprint-override"><code>lambda a,b:str(a*b)==str(~-a*b)[::-1] </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##TYzNCsIwEITveYrFUyKxpP@1kB59Am/qIaUtBtImJFHoxVevDUjrYZeZnW/WzP6pp3QZ@H1RYmw7AYK2tfMWi2NLOA/qcwr6Vten@LHI0Wjrwc0ODdqCAjkFEznfyalGIKnmKnJGSY8PvDkQFD7y4ygM7t9CUfkLCaEIjJWTxytAh7AJDQjWhCwFnIE3cLWvHmWQB30RyvUohSQuqy1LM0hYubMlVDtbMAbxOtshK1Zf7XQVl5Cz9K8BZ8a2/As" rel="noreferrer" title="Python 3 – Try It Online">Try it online!</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T22:01:38"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242001"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242001" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short 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9 6 over ! 9 6 9 * ! 9 54 dup ! 9 54 54 present ! 9 54 "54" reverse ! 9 54 "45" dec> ! 9 54 45 - ! 9 9 = ! t </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T21:34:07"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="241998"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/241998" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/241998/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-241998" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/241998/revisions" title="show all edits to this post" class="js-gps-track" data-gps-track="post.click({ item: 4, priv: 0, post_type: 2 })">edited <span title="2022-01-30 01:34:45Z" class="relativetime">Jan 30 at 1:34</span></a> </div> <div class="user-gravatar32"> </div> <div class="user-details"> <div class="-flair"> </div> </div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-29 21:34:07Z" class="relativetime">Jan 29 at 21:34</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/97916/chunes"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/B0og9.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/97916/chunes">chunes</a><span class="d-none" itemprop="name">chunes</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">6,030</span><span title="1 gold badge" aria-hidden="true"><span class="badge1"></span><span class="badgecount">1</span></span><span class="v-visible-sr">1 gold badge</span><span title="6 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">6</span></span><span class="v-visible-sr">6 silver badges</span><span title="26 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">26</span></span><span class="v-visible-sr">26 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-241998" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="241998" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-241998" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. 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class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242012/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/DennisMitchell/jelly" rel="noreferrer">Jelly</a>, 6 <a href="https://web.archive.org/web/20220202015155/https://github.com/DennisMitchell/jelly/wiki/Code-page" rel="noreferrer">bytes</a></h1> <pre><code>’×ṚḌ⁼× </code></pre> <p>A dyadic Link accepting <span class="math-container">\$a\$</span> and <span class="math-container">\$b\$</span> that yields <code>1</code> if <span class="math-container">\$a\times b = \text{reversed}( (a - 1)\times b )\$</span>, <code>0</code> if not.</p> <p><strong><a href="https://web.archive.org/web/20220202015155/https://tio.run/##ASAA3/9qZWxsef//4oCZw5fhuZrhuIzigbzDl////zb/OTAwOQ" rel="noreferrer" title="Jelly – Try It Online">Try it online!</a></strong> Or see the <a href="https://web.archive.org/web/20220202015155/https://tio.run/##y0rNyan8//9Rw8zD0x/unPVwR8@jxj2Hp/8/vFz/UdOa//@jo810FCxjdRSiTXQUTEG0sY6CkaG5BZgJFDMyMAdLm@sogMXMDAx0FAwNDMBazEBMC7C8hSFQhamBMVgN0EgDA7CwsZEhUKNhbCwA" rel="noreferrer" title="Jelly – Try It Online">test-suite</a>.</p> <h3>How?</h3> <pre><code>’×ṚḌ⁼× - Link: a, b ’ - a-1 × - (a-1) times b Ṛ - reverse the digits of (a-1)×b Ḍ - convert back to an integer × - a×b ⁼ - equal? </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T01:37:10"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242012"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242012" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242012/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242012" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242012/revisions" title="show all edits to this post" class="js-gps-track" data-gps-track="post.click({ item: 4, priv: 0, post_type: 2 })">edited <span title="2022-01-30 02:10:32Z" class="relativetime">2 days ago</span></a> </div> <div class="user-gravatar32"> </div> <div class="user-details"> <div class="-flair"> </div> </div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> answered <span title="2022-01-30 01:37:10Z" class="relativetime">Jan 30 at 1:37</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/53748/jonathan-allan"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/fIyIX.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/53748/jonathan-allan">Jonathan Allan</a><span class="d-none" itemprop="name">Jonathan Allan</span> <div class="-flair"> <span class="reputation-score" title="reputation score 87,801" dir="ltr">87.8k</span><span title="7 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">7</span></span><span class="v-visible-sr">7 gold badges</span><span title="58 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">58</span></span><span class="v-visible-sr">58 silver badges</span><span title="242 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">242</span></span><span class="v-visible-sr">242 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount">3</span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242012" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="242012" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-545433" class="comment js-comment " data-comment-id="545433" data-comment-owner-id="109916" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">how do you code in jelly?</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/109916/dialfrost" title="871 reputation" class="comment-user">DialFrost</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 04:05:34Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> </div> </div> </li> <li id="comment-545435" class="comment js-comment " data-comment-id="545435" data-comment-owner-id="103854" data-comment-score="2"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">2</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">@DialFrost the same way you code in other languages:P</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/103854/pygamer0" title="845 reputation" class="comment-user">PyGamer0</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 04:43:08Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> </div> </div> </li> <li id="comment-545464" class="comment js-comment " data-comment-id="545464" data-comment-owner-id="53748" data-comment-score="1"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">1</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">@DialFrost see the <a href="https://web.archive.org/web/20220202015155/https://github.com/DennisMitchell/jellylanguage/wiki/Tutorial" rel="nofollow noreferrer">tutorial</a> to get started.</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/53748/jonathan-allan" title="87,801 reputation" class="comment-user">Jonathan Allan</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 13:19:07Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> </div> </div> </li> </ul> </div> <div id="comments-link-242012" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242014"></a> <div id="answer-242014" class="answer js-answer" data-answerid="242014" data-score="5" data-position-on-page="6" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242014"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="5"> 5 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242014/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1>Python 2, 31 bytes</h1> <pre><code>lambda a,b:`a*b`==`a*b-b`[::-1] </code></pre> <p>Using the logic that <span class="math-container">$$ ab = \operatorname{rev}( (a-1)b ) \iff ab = \operatorname{rev}(ab-b) $$</span> -2 thx to @dingledooper</p> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##TUxLDoIwEN33FBNWYAop/09Sl57AnZrQBohNCiW0Ljh9pUbBxcyb95k3r@appsQO9G4lG3nHgGHetOzEW0odhLy9NU0YP6wYZ7UY0KtGg1pAgpgcibTpxNQgEFhRGelZCuN7QM/gBci1UfEVf3QyPguwA75J8/IRMMeD2wFWgS2gdgXX5dWjDHJ3X5jUPUohictq99IMElIe2RKqI1sQAvE2u5AVG6@OdBWXkJP07wNqQnb/DQ" rel="nofollow noreferrer">Try it online!</a></p> <h2>Other solutions:</h2> <h3>Python 2, 31 bytes</h3> <pre><code>lambda a,b:`a*b`[::-1]==`a*b-b` </code></pre> <p>Using the logic that <span class="math-container">$$ \operatorname{rev}(ab) = (a-1)b \iff \operatorname{rev}(ab) = ab-b $$</span> -2 thx to @dingledooper</p> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##TYzLDoIwEEX3/YoJKzCFlPcjqUu/wJ2a0AaITQoltC74@kqNgot5nDt37ryap5oSO9C7lWzkHQOGedOyE29vTRPGD0odhLy1YpzVYkCvGg1qAQlichBp04mpQSCwojLSsxTG94CewQuQS6PiK/5wMj4LsBt8k@blI2COB9cDrAJbQO0CrsurRxnkbr8wqXuUQhKX1X5LM0hIeXhLqA5vQQjEW@1CVmxcHe4qLiEn6d8H1ITs9zc" rel="nofollow noreferrer">Try it online!</a></p> <h3>Python 2, 34 bytes</h3> <pre><code>lambda a,b:a*b-int(`a*b`[::-1])==b </code></pre> <p>Using the logic that <span class="math-container">$$ ab - \operatorname{rev}(ab) =b $$</span></p> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##TUxLDsIgEN1ziokrMdjQj/0luPQE7tREiG0koaUBXPT0CEZbFzPzfvOm2T31mPmeXb3ig3hw4ES0fCf2cnTbewD3S9vu0xtmTHg5TNo4sLNFvTagQI6RJNY95NgikEQzldhJSbfdADvCBqNYyORX/NHQzTGJRwRpMh@BCNLHjYnGvoQmFpzNq0MFHCI@cWU7lEOWVvXi5QVktFqzFdRrtqQU0jCLUJSB12u6Tis40PzvAxpKF/8N" rel="nofollow noreferrer">Try it online!</a></p> <p>^Credits to @ovs for the equations!</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T02:50:11"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242014"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242014" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242014/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242014" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242014/revisions" title="show all edits to this post" class="js-gps-track" data-gps-track="post.click({ item: 4, priv: 0, post_type: 2 })">edited <span title="2022-01-31 02:49:11Z" class="relativetime">yesterday</span></a> </div> <div class="user-gravatar32"> </div> <div class="user-details"> <div class="-flair"> </div> </div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-30 02:50:11Z" class="relativetime">2 days ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/109916/dialfrost"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://lh3.googleusercontent.com/a-/AOh14GgkvqOkqaYgZ4uyyOH5DAoR6X3BoOq-89TvuOY9DA=k-s64" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/109916/dialfrost">DialFrost</a><span class="d-none" itemprop="name">DialFrost</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">871</span><span title="1 silver badge" aria-hidden="true"><span class="badge2"></span><span class="badgecount">1</span></span><span class="v-visible-sr">1 silver badge</span><span title="21 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">21</span></span><span class="v-visible-sr">21 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount">2</span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242014" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="242014" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-545429" class="comment js-comment " data-comment-id="545429" data-comment-owner-id="88546" data-comment-score="3"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="cool">3</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy"><code>(a-1)*b</code> -> <code>a*b-b</code></span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/88546/dingledooper" title="15,735 reputation" class="comment-user">dingledooper</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 03:47:31Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> </div> </div> </li> <li id="comment-545432" class="comment js-comment " data-comment-id="545432" data-comment-owner-id="109916" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">thx @dingledooper! im so dumb i didnt see that</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/109916/dialfrost" title="871 reputation" class="comment-user">DialFrost</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-30 03:55:13Z, License: CC BY-SA 4.0" class="relativetime-clean">2 days ago</span></span> <span title="this comment was edited 1 time"> <svg aria-hidden="true" class="va-text-bottom o50 svg-icon iconPencilSm" width="14" height="14" viewbox="0 0 14 14"><path d="m11.1 1.71 1.13 1.12c.2.2.2.51 0 .71L11.1 4.7 9.21 2.86l1.17-1.15c.2-.2.51-.2.71 0ZM2 10.12l6.37-6.43 1.88 1.88L3.88 12H2v-1.88Z"/></svg> </span> </div> </div> </li> </ul> </div> <div id="comments-link-242014" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="241993"></a> <div id="answer-241993" class="answer js-answer" data-answerid="241993" data-score="4" data-position-on-page="7" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="241993"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="4"> 4 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/241993/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/Vyxal/Vyxal" rel="nofollow noreferrer">Vyxal</a>, 7 bytes</h1> <pre><code>:‹"*÷Ṙ= </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://vyxal.pythonanywhere.com/#WyIiLCIiLCI64oC5XCIqw7fhuZg9IiwiIiwiNlxuOSJd" rel="nofollow noreferrer">Try it Online!</a></p> <pre><code> " # Pair the first input with :‹ # Itself decremented * # Multiply both by the second input ÷ # Push both to the stack Ṙ= # Is one reversed equal to the other? </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T20:41:10"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="241993"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/241993" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/241993/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-241993" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> answered <span title="2022-01-29 20:41:10Z" class="relativetime">Jan 29 at 20:41</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/100664/emanresu-a"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/NE9LE.png?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/100664/emanresu-a">emanresu A</a><span class="d-none" itemprop="name">emanresu A</span> <div class="-flair"> <span class="reputation-score" title="reputation score 22,820" dir="ltr">22.8k</span><span title="3 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">3</span></span><span class="v-visible-sr">3 gold badges</span><span title="35 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">35</span></span><span class="v-visible-sr">35 silver badges</span><span title="125 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">125</span></span><span class="v-visible-sr">125 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-241993" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="241993" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-241993" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242003"></a> <div id="answer-242003" class="answer js-answer" data-answerid="242003" data-score="4" data-position-on-page="8" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242003"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="4"> 4 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242003/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/somebody1234/Charcoal" rel="nofollow noreferrer">Charcoal</a>, 13 bytes</h1> <pre><code>ＮθＮη⁼×θη⮌×⊖θη </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##S85ILErOT8z5/98zr6C0xK80Nym1SKNQ05oLmZ8B5AcUZeaVaLgWlibmFGuEZOamFmsU6ihkaOooBKWWpRYVp0IFXVKTi1JzU/NKUlOA5oBUAIH1///GJgpGBuaW/3XLcgA" rel="nofollow noreferrer" title="Charcoal – Try It Online">Try it online!</a> Link is to verbose version of code. Outputs a Charcoal boolean, i.e. <code>-</code> for a reversed pair, nothing if not. Explanation:</p> <pre><code>Ｎθ First input as a number Ｎη Second input as a number θ First input × Multiplied by η Second input ⁼ Equals θ First input ⊖ Decremented × Multiplied by η Second input ⮌ Reversed Implicitly print </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T22:12:16"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242003"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242003" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242003/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242003" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> answered <span title="2022-01-29 22:12:16Z" class="relativetime">Jan 29 at 22:12</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/17602/neil"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/4538cb9de4914a875d13da50c7c406ad?s=64&d=identicon&r=PG&f=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/17602/neil">Neil</a><span class="d-none" itemprop="name">Neil</span> <div class="-flair"> <span class="reputation-score" title="reputation score 135,703" dir="ltr">136k</span><span title="10 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">10</span></span><span class="v-visible-sr">10 gold badges</span><span title="59 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">59</span></span><span class="v-visible-sr">59 silver badges</span><span title="243 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">243</span></span><span class="v-visible-sr">243 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242003" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242003" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242003" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242007"></a> <div id="answer-242007" class="answer js-answer" data-answerid="242007" data-score="4" data-position-on-page="9" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242007"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="4"> 4 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" 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<pre><code>f(a,b)=d=digits;d(a*b)==Vecrev(d(a--*b)) </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##HYzbCoMwDIZfJXjVjhRSndox3GPsRrzIPFGQUZwM9vRdzFW@/5TEe3RrynkxjC/bTd0U13h87pPhi@juOY/7/DUinRPDZk5p@xkG94C0x/chWJyigJG3zSwIbC1C3zcIt0HgilCft0IofRsUxSup1bhFUK8hQvBEOmlODJoHL42aKu3ISyK1q9LL0A@DzX8" rel="nofollow noreferrer" title="Pari/GP – Try It Online">Try it online!</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T23:48:46"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242007"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242007" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" 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aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-29 23:48:46Z" class="relativetime">Jan 29 at 23:48</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/9288/alephalpha"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/0695797b6063143ff79efe5a98a74361?s=64&d=identicon&r=PG" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/9288/alephalpha">alephalpha</a><span class="d-none" itemprop="name">alephalpha</span> <div class="-flair"> <span class="reputation-score" title="reputation score 29,687" dir="ltr">29.7k</span><span title="5 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">5</span></span><span class="v-visible-sr">5 gold badges</span><span title="40 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">40</span></span><span class="v-visible-sr">40 silver badges</span><span title="114 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">114</span></span><span class="v-visible-sr">114 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242007" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242007" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242008"></a> <div id="answer-242008" class="answer js-answer" data-answerid="242008" data-score="4" data-position-on-page="10" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242008"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="4"> 4 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242008/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1>JavaScript (ES6), 41 bytes</h1> <p>Expects <code>(a)(b)</code>. Returns a Boolean value.</p> <pre class="lang-javascript prettyprint-override"><code>a=>b=>[...a*b+''].reverse().join``==a*b-b </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##fZBNDoIwEEb3noIdHQ2l5bcsytITuDMmFCwGQqhpletja0yMBpjFbOblfTPTi0mYRnf3RzCqq5xbPgte1rw8Y4zFvj74/gVrOUltJALcq26sKs7tJKjnRo1GDRIP6oZalAEqADxXYeid9FPufoEEUPoFjmIw/0QMKKI5c9CyIraOiOQuZxnIAbHtjIwQQNQ2WCOSzAFsPYRRG5OSeF3hfkFIsXFIRO2m9AO8FfML" rel="nofollow noreferrer" title="JavaScript (Node.js) – Try It Online">Try it online!</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T23:56:53"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242008"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242008" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242008/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242008" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-29 23:56:53Z" class="relativetime">Jan 29 at 23:56</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/58563/arnauld"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/HifFH.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/58563/arnauld">Arnauld</a><span class="d-none" itemprop="name">Arnauld</span> <div class="-flair"> <span class="reputation-score" title="reputation score 161,890" dir="ltr">162k</span><span title="15 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">15</span></span><span class="v-visible-sr">15 gold badges</span><span title="159 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">159</span></span><span class="v-visible-sr">159 silver badges</span><span title="575 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">575</span></span><span class="v-visible-sr">575 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242008" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242008" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242008" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242142"></a> <div id="answer-242142" class="answer js-answer" data-answerid="242142" data-score="4" data-position-on-page="11" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242142"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" 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noreferrer">tinylisp</a>, 76 bytes</h1> <pre><code>(load library (d f(q((a b)(e(to-base 10(*(- a 1)b))(reverse(to-base 10(* a b </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##VYtBCoMwFET3nmKWPwXhx2iix0kwQiDUNkrB06fB301X85g3c6bnldPxqpXy7lfkFIovV0crNnoTeQRFkc69D/6I0EwP6uGhVVCKSvzEcvzrJkOlDRaL6lqOmO40GLSbBUcM7EQ7SGeZ253lYhvO4mftMLGRDRZmqc2gm7pR829dvw" rel="nofollow noreferrer" title="tinylisp – Try It Online">Try it online!</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-02-01T06:23:42"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242142"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242142" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" 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href="/web/20220202015155/https://codegolf.stackexchange.com/users/80214/razetime"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/ZMbLM.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/80214/razetime">Razetime</a><span class="d-none" itemprop="name">Razetime</span> <div class="-flair"> <span class="reputation-score" title="reputation score 24,009" dir="ltr">24k</span><span title="3 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">3</span></span><span class="v-visible-sr">3 gold badges</span><span title="17 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">17</span></span><span class="v-visible-sr">17 silver badges</span><span title="68 bronze badges" 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242002"></a> <div id="answer-242002" class="answer js-answer" data-answerid="242002" data-score="3" data-position-on-page="12" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242002"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="3"> 3 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242002/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/m-ender/retina/wiki/The-Language/a950ad7d925ec9316e3e2fb2cf5d49fd15d23e3d" rel="nofollow noreferrer">Retina 0.8.2</a>, 55 bytes</h1> <pre><code>\d+ $* 1, , 1(?=.*,(1+)) $1 , ,$` 1+ $.& +`(.),\1 , ^,$ </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##FYu7CgIxFAX78x1Rks0h3Jvs5lGIpT@xSAQtbCwW/z/GamCYOV7f9@cxTvbWx/70MAuUINReL2GhVe8cjE5D06EzCGf4boPj/rd3mjEyG1ZuSIxaKtLKKKWhsCKLUEWw5onaULVwk4S5iDSkqKz6Aw" rel="nofollow noreferrer" title="Retina 0.8.2 – Try It Online">Try it online!</a> Link includes test cases. Explanation:</p> <pre><code>\d+ $* </code></pre> <p>Convert to unary.</p> <pre><code>1, , </code></pre> <p>Decrement <code>a</code>.</p> <pre><code>1(?=.*,(1+)) $1 </code></pre> <p>Multiply <code>a-1</code> by <code>b</code>.</p> <pre><code>, ,$` </code></pre> <p>Add that to <code>b</code> giving <code>(a-1)b,ab</code>.</p> <pre><code>1+ $.& </code></pre> <p>Convert to decimal.</p> <pre><code>+`(.),\1 , ^,$ </code></pre> <p>Test whether the results are mirror images of each other.</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T22:08:50"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242002"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242002" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242002/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242002" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> answered <span title="2022-01-29 22:08:50Z" class="relativetime">Jan 29 at 22:08</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/17602/neil"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/4538cb9de4914a875d13da50c7c406ad?s=64&d=identicon&r=PG&f=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/17602/neil">Neil</a><span class="d-none" itemprop="name">Neil</span> <div class="-flair"> <span class="reputation-score" title="reputation score 135,703" dir="ltr">136k</span><span title="10 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">10</span></span><span class="v-visible-sr">10 gold badges</span><span title="59 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">59</span></span><span class="v-visible-sr">59 silver badges</span><span title="243 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">243</span></span><span class="v-visible-sr">243 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242002" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242002" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242002" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242005"></a> <div id="answer-242005" class="answer js-answer" data-answerid="242005" data-score="3" data-position-on-page="13" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242005"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="3"> 3 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242005/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/http://www.red-lang.org/" rel="nofollow noreferrer">Red</a>, <sup><s>47</s></sup> 45 bytes</h1> <pre><code>func[a b][(to""a * b)= reverse to""a - 1 * b] </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##JYxLCsIwAET3PcWjKxWEpGmbRPASbkMW/STopi2xev0YdWAYePAmhTnfwux8FS85vpbJDYzeHfa1rgdOjMcrKbxDegb@7Iz8cp/jmsIw3fkZuB5LS4eikdqgWhqhLRpDLwSytO3LGIuRmk4oiiKERTWyIO8qSrb0WHYi5bTy@QM" rel="nofollow noreferrer" title="Red – Try It Online">Try it online!</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-29T23:15:42"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242005"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242005" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242005/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242005" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-29 23:15:42Z" class="relativetime">Jan 29 at 23:15</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/97916/chunes"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/B0og9.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/97916/chunes">chunes</a><span class="d-none" itemprop="name">chunes</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">6,030</span><span title="1 gold badge" aria-hidden="true"><span class="badge1"></span><span class="badgecount">1</span></span><span class="v-visible-sr">1 gold badge</span><span title="6 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">6</span></span><span class="v-visible-sr">6 silver badges</span><span title="26 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">26</span></span><span class="v-visible-sr">26 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242005" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242005" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242005" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242029"></a> <div id="answer-242029" class="answer js-answer" data-answerid="242029" data-score="3" data-position-on-page="14" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242029"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="3"> 3 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242029/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://dyalog.com/" rel="nofollow noreferrer">APL (Dyalog Unicode)</a>, 9 bytes</h1> <p>Anonymous tacit infix function, taking <span class="math-container">\$a\$</span> as left argument and <span class="math-container">\$b\$</span> as right argument.</p> <pre class="lang-apl prettyprint-override"><code>×≡∘⌽⍥⍕×-⊢ </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##SyzI0U2pTMzJT9dNrShJzUtJTfn///D0R50LH3XMeNSz91Hv0ke9Uw9P133Uteh/2qO2CY96@x51NT/qXfOod8uh9caP2iY@6psaHOQMJEM8PIP/mymkKVgqPOqdqxBSVJrKZQLkmoK5bok5xalcxkC@kaG5BUKFMUiJkYE5kiZzoIgFkiYzAwOgiCGQRIiZmIGFLJC0WRiCNJoaGCNrBTnHwABJlbGRIch4Q4QiAA" rel="nofollow noreferrer" title="APL (Dyalog Extended) – Try It Online">Try it online!</a> (Uses Extended because TIO hasn't updated to 18.0)</p> <p><code>×</code> [Does] the product</p> <p><code>≡∘</code> match the…</p> <p> <code>⌽⍥</code> reversed, when both are…</p> <p> <code>⍕</code> stringified</p> <p><code>×</code> product</p> <p><code>-</code> minus</p> <p><code>⊢</code> the right argument[?]</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T10:19:24"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242029"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242029" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242033"></a> <div id="answer-242033" class="answer js-answer" data-answerid="242033" data-score="2" data-position-on-page="15" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242033"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" 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class="lang-c prettyprint-override"><code>c;r;f(a,b){for(r=0,c=~-a*b;c;c/=10)r+=9*r+c%10;r-=a*b;} </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##bVHZboMwEHzPV2yRkDiMYifNgVz3pepXNFEFxqSoLYlspKJG9NNL11xKoiKzeGd2BhjL6CBl20quee4lJPXP@VF7WlAixU@UBCmXXM4Fo74ORRzoULqMch0JSzVtUVbwmRSl58N5BnhZoFKmMq/Jyx4EnNcE7gksceFjQ2BNKSKIbpntEF@wht9o014bE1gRWLDNFivdYIsbZg0Y3VqSom9MqSUuTVR9UrJSWe/CCFhFt@i4H@ogksfSVCDfEh1gVfJd6V7r7Ornxa6On/BeOQQu@6UzqDEx8Ox7izJTNcooH7YPYIpvdcy98Yv8@QAEE8IhDLtpvzPrYxz/JEG3Mc5uaM@v@HTi0395g/ydPVhI/WtGITPldCs9aRzJPcfNCLgZRI@2umZXYgTWi4AhU1BGCLUf3JtZ0/7K/CM5mDb6@gM" rel="nofollow noreferrer" title="C (gcc) – Try It Online">Try it online!</a></p> <p>Inputs two integers <span class="math-container">\$a\$</span> and <span class="math-container">\$b\$</span>.<br/> Returns a falsy value if these two numbers are a reversed multiple pair or a truthy value otherwise.</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> 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class="lang-ruby prettyprint-override"><code>->a,b{"#{a*=b}"==(a-b).digits*''} </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##KypNqvyfZvtf1y5RJ6laSbk6Ucs2qVbJ1lYjUTdJUy8lMz2zpFhLXb32f4FCWrSZjmUsF4hhrmMBYZgZGOgYGhhAOCZmQLaFZex/AA" rel="nofollow noreferrer" title="Ruby – Try It Online">Try it online!</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T20:03:33"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242049"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242049" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a 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class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242028/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1>BQN, <s>33</s> 22 Bytes</h1> <p><s>This seems too long.</s></p> <p>A little better.</p> <pre><code>{(𝕨×𝕩)=•BQN⌽•Fmt𝕩×𝕨-1} </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://mlochbaum.github.io/BQN/try.html#code=RuKGkHso8J2VqMOX8J2VqSk94oCiQlFO4oy94oCiRm108J2VqcOX8J2VqC0xfQo2IEYgOQ==" rel="nofollow noreferrer">Try it!</a></p> <p><em>¯11 bytes thanks to @Razetime</em></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T09:55:31"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242028"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242028" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242025"></a> <div id="answer-242025" class="answer js-answer" data-answerid="242025" data-score="1" data-position-on-page="18" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242025"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="1"> 1 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242025/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1>APL+WIN, <s>22</s> 20 bytes</h1> <p>Prompts for a then b. Minus 2 bytes using rearrangement logic</p> <pre><code>(⍎⌽⍕n-b)=n←(b←⎕)×a←⎕ </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##JYuxDcIwEEX7m8JlUlg628R2CgZAAjGDE2SEZAWkVCwAFCSiiZiGik28iLkTje/pv@dwSfJwDel8lH0K43jqS56X3TbfXgaINnsiBflxj6XK05yfnzwtg@zq9UCm6uihrP6@w58KpVAiWGghwkpAQ8cI0Mp5Jlo0OnZOAC8WUYBC5NoyeZZekW7QcCCgReTRaEV/1A8" rel="nofollow noreferrer" title="APL (Dyalog Classic) – Try It Online">Try it online! Thanks to Dyalog Classic</a></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T09:25:00"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242025"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242025" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242025/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242025" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242025/revisions" title="show all edits to this post" class="js-gps-track" data-gps-track="post.click({ item: 4, priv: 0, post_type: 2 })">edited <span title="2022-01-30 10:14:47Z" class="relativetime">2 days ago</span></a> </div> <div class="user-gravatar32"> </div> <div class="user-details"> <div class="-flair"> </div> </div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-30 09:25:00Z" class="relativetime">2 days ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/6949/graham"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/ee1f7de870726aeada0144162101a1ae?s=64&d=identicon&r=PG" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/6949/graham">Graham</a><span class="d-none" itemprop="name">Graham</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">4,516</span><span title="11 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">11</span></span><span class="v-visible-sr">11 silver badges</span><span title="9 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">9</span></span><span class="v-visible-sr">9 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242025" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242025" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242025" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242032"></a> <div id="answer-242032" class="answer js-answer" data-answerid="242032" data-score="1" data-position-on-page="19" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242032"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="1"> 1 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242032/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/m-ender/retina/wiki/The-Language" rel="nofollow noreferrer">Retina</a>, 41 bytes</h1> <pre><code>L$`.+, *$'*_,$($^$.(*$'*))*_$'* ^(_+),\1$ </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##FcsxDgIhEEbh/j/HGIGdbGaAheEENh7BLGthYWNh9v6I1ZdXvO/rfH@eOi7udow7HevCCHQNncnRTqv7h/ehT7C7vnh@KI1RuCHzhsRRqyFljlIbKhuKCKsIcplYg2nlTRLmItKQorLpDw" rel="nofollow noreferrer" title="Retina – Try It Online">Try it online!</a> Link includes test cases. Explanation: Based on @ovs' 05AB1E answer.</p> <pre><code>L$`.+, </code></pre> <p>Match <code>a</code> as <code>$&</code> (Retina ignores the trailing comma when performing arithmetic) and <code>b</code> as <code>$'</code> and replace the whole input with the result.</p> <pre><code>*$'*_,$($^$.(*$'*))*_$'* </code></pre> <p>Calculate <code>a*b</code> and also <code>rev(a*b)+b</code> in unary.</p> <pre><code>^(_+),\1$ </code></pre> <p>See whether they are the same.</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T11:04:07"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242032"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242032" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242032/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242032" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> answered <span title="2022-01-30 11:04:07Z" class="relativetime">2 days ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/17602/neil"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/4538cb9de4914a875d13da50c7c406ad?s=64&d=identicon&r=PG&f=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/17602/neil">Neil</a><span class="d-none" itemprop="name">Neil</span> <div class="-flair"> <span class="reputation-score" title="reputation score 135,703" dir="ltr">136k</span><span title="10 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">10</span></span><span class="v-visible-sr">10 gold badges</span><span title="59 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">59</span></span><span class="v-visible-sr">59 silver badges</span><span title="243 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">243</span></span><span class="v-visible-sr">243 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242032" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242032" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242032" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. 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Duplicate pd # Product of array j # Swap p^ # Push elements to stack (b, a) -. # Decrement .* # Product <- # Reverse digits == # Equal </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T19:19:51"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242045"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242045" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242045/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242045" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> answered <span title="2022-01-30 19:19:51Z" class="relativetime">2 days ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/91386/deathincarnate"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/27fe2f16a81dae3425f3f2b105d469b8?s=64&d=identicon&r=PG&f=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/91386/deathincarnate">DeathIncarnate</a><span class="d-none" itemprop="name">DeathIncarnate</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">1,560</span><span title="3 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">3</span></span><span class="v-visible-sr">3 silver badges</span><span title="8 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">8</span></span><span class="v-visible-sr">8 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242045" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242045" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242045" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242103"></a> <div id="answer-242103" class="answer js-answer" data-answerid="242103" data-score="1" data-position-on-page="21" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242103"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" 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class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242103/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://www.haskell.org/" rel="nofollow noreferrer">Haskell</a>, <s>43</s> 33 bytes</h1> <pre class="lang-hs prettyprint-override"><code>a?b=a*b==read(reverse$show$a*b-b) </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##XY7NCsIwEITvfYo95KCCsNu/pIfQZ9nQQIu1laTo48dEPKwev4@ZYWaON7@uKfHoLF@ctcHzdAr@6UP0Ks77S2V9ded052UDC9NewSMs2wEKoIcRBsFN5pq0kaotDrWMtaVHaIb/KcSfWFadYJ1ZTveInx0UzlBJddjICzWVJglF@H0AVXoD" rel="nofollow noreferrer" title="Haskell – Try It Online">Try it online!</a></p> <ul> <li>I haven't thought <code>reverse</code> was available in prelude, no reason to use foldl(flip(:))""String</li> </ul> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-31T16:39:03"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242103"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242103" rel="nofollow" itemprop="url" 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class="relativetime">yesterday</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/84844/aztecco"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://www.gravatar.com/avatar/36917c22a526c68f7bf3d3ea69a5c643?s=64&d=identicon&r=PG&f=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/84844/aztecco">AZTECCO</a><span class="d-none" itemprop="name">AZTECCO</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">7,940</span><span title="1 gold badge" aria-hidden="true"><span class="badge1"></span><span class="badgecount">1</span></span><span class="v-visible-sr">1 gold badge</span><span title="11 silver badges" aria-hidden="true"><span class="badge2"></span><span 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242140"></a> <div id="answer-242140" class="answer js-answer" data-answerid="242140" data-score="1" data-position-on-page="22" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242140"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" 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class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242140/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://geogebra.org/" rel="nofollow noreferrer">GeoGebra</a>, <s>86</s> 77 bytes</h1> <pre><code>a=6 b=9 s=Text(ab-b) o=FromBase(Sum(Zip(Take(s,c,c),c,Length(s)…1)),10)==ab </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://www.geogebra.org/calculator/m3g8bgb6" rel="nofollow noreferrer">Try It On GeoGebra!</a></p> <p>Input is <code>a</code> and <code>b</code>, output is <code>o</code> as <code>true</code> if <code>a</code> and <code>b</code> are a reversed multiple pair, <code>false</code> otherwise.</p> <p>The example input shown in the code is <code>a=6</code> and <code>b=9</code>, but you can change these values to whatever you want.</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-02-01T05:41:15"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242140"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a 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user-hover"> <div class="user-action-time"> answered <span title="2022-02-01 05:41:15Z" class="relativetime">20 hours ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/96039/aiden-chow"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://lh3.googleusercontent.com/-j6HBVvObKqE/AAAAAAAAAAI/AAAAAAAAADU/3gJkgFzaAz0/photo.jpg?sz=64" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/96039/aiden-chow">Aiden Chow</a><span class="d-none" itemprop="name">Aiden Chow</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">1,465</span><span title="1 silver badge" aria-hidden="true"><span class="badge2"></span><span class="badgecount">1</span></span><span class="v-visible-sr">1 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242039"></a> <div id="answer-242039" class="answer js-answer" data-answerid="242039" data-score="0" data-position-on-page="23" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242039"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="0"> 0 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242039/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://php.net/" rel="nofollow noreferrer">PHP</a>, 79 bytes</h1> <pre class="lang-php prettyprint-override"><code>$a=trim(fgets(STDIN));$b=trim(fgets(STDIN));echo $a*$b==(int)strrev($b*($a-1)); </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##K8go@G9jXwAkVRJtS4oyczXS0lNLijWCQ1w8/TQ1rVWSsImmJmfkK6gkagFlbTUy80o0i0uKilLLNFSStDRUEnUNgUr@/zfjsgQA" rel="nofollow noreferrer" title="PHP – Try It Online">Try it online!</a></p> <p>With the help of Github Copilot</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-30T14:51:37"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242039"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242039" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242039/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242039" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-30 14:51:37Z" class="relativetime">2 days ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/106959/fmbalbuena"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/NbBEN.png?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/106959/fmbalbuena">Fmbalbuena</a><span class="d-none" itemprop="name">Fmbalbuena</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">2,023</span><span title="1 gold badge" aria-hidden="true"><span class="badge1"></span><span class="badgecount">1</span></span><span class="v-visible-sr">1 gold badge</span><span title="4 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">4</span></span><span class="v-visible-sr">4 silver badges</span><span title="36 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">36</span></span><span class="v-visible-sr">36 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount">1</span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242039" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="242039" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-545618" class="comment js-comment " data-comment-id="545618" data-comment-owner-id="14732" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">Instead of all of this, you can just do <code>fn($a,$b)=>$a*$b==+strrev($b*($a-1));</code>. This creates an anonymous function and does the casting to a number in fewer bytes. This syntax was introduced in PHP 8.0. You can see it working for yourself here: <a href="https://web.archive.org/web/20220202015155/http://sandbox.onlinephpfunctions.com/code/d26cb3ea5513512044fd100d5cc62e306e8e6e23" rel="nofollow noreferrer">sandbox.onlinephpfunctions.com/code/…</a></span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/14732/ismael-miguel" title="7,355 reputation" class="comment-user">Ismael Miguel</a> </div> <span class="comment-date" dir="ltr"><span title="2022-01-31 17:41:14Z, License: CC BY-SA 4.0" class="relativetime-clean">yesterday</span></span> </div> </div> </li> </ul> </div> <div id="comments-link-242039" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242088"></a> <div id="answer-242088" class="answer js-answer" data-answerid="242088" data-score="0" data-position-on-page="24" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242088"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="0"> 0 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242088/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1><a href="https://web.archive.org/web/20220202015155/https://github.com/maxbergmark/mathgolf/blob/master/math_golf.txt" rel="nofollow noreferrer">MathGolf</a>, 7 <a href="https://web.archive.org/web/20220202015155/https://github.com/maxbergmark/mathgolf/blob/master/code_page.py" rel="nofollow noreferrer">bytes</a></h1> <pre><code>`(*x¬*= </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##HYqpEYAwEEX9r2IlE/U350bQCxhAwGAQFEUVNBYyyHcc87Wt5760Ng3ufh83tpalIojXYghRPEtFzKK0ip7IjpJQxJDJ7gnTIokBwauYQvnfHw" rel="nofollow noreferrer">Try it online.</a></p> <p><strong>Explanation:</strong></p> <pre class="lang-python prettyprint-override"><code>` # Duplicate the top two items, using the implicit inputs # STACK: b,a,b,a ( # Decrease the top item # STACK: b,a,b,a-1 * # Multiply the top two together # STACK: b,a,b*(a-1) x # Reverse the top integer # STACK: b,a,reverse(b*(a-1)) ¬ # Reverse rotate the stack: # STACK: reverse(b*a(-1)),b,a * # Multiply the top two again # STACK: reverse(b*a(-1)),b*a = # Check if the two are equal # STACK: reverse(b*a(-1))==b*a # (after which the entire stack joined together is output implicitly) </code></pre> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-31T12:55:21"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242088"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242088" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook twitter " data-se-share-sheet-location="2" data-se-share-sheet-license-url="https%3a%2f%2fcreativecommons.org%2flicenses%2fby-sa%2f4.0%2f" data-se-share-sheet-license-name="CC BY-SA 4.0" data-s-popover-placement="bottom-start">Share</a> </div> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242088/edit" class="js-suggest-edit-post js-gps-track" data-gps-track="post.click({ item: 6, priv: 0, post_type: 2 })" title="">Improve this answer</a> </div> <div class="flex--item"> <button type="button" id="btnFollowPost-242088" class="s-btn s-btn__link js-follow-post js-follow-answer js-gps-track" data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info "> <div class="user-action-time"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242088/revisions" title="show all edits to this post" class="js-gps-track" data-gps-track="post.click({ item: 4, priv: 0, post_type: 2 })">edited <span title="2022-01-31 13:12:57Z" class="relativetime">yesterday</span></a> </div> <div class="user-gravatar32"> </div> <div class="user-details"> <div class="-flair"> </div> </div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-31 12:55:21Z" class="relativetime">yesterday</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/52210/kevin-cruijssen"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/MefSP.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/52210/kevin-cruijssen">Kevin Cruijssen</a><span class="d-none" itemprop="name">Kevin Cruijssen</span> <div class="-flair"> <span class="reputation-score" title="reputation score 96,404" dir="ltr">96.4k</span><span title="8 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">8</span></span><span class="v-visible-sr">8 gold badges</span><span title="126 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">126</span></span><span class="v-visible-sr">126 silver badges</span><span title="324 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">324</span></span><span class="v-visible-sr">324 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount"></span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242088" class="comments js-comments-container bt bc-black-075 mt12 dno" data-post-id="242088" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> </ul> </div> <div id="comments-link-242088" data-rep="50" data-anon="true"> <a class="js-add-link comments-link disabled-link" title="Use comments to ask for more information or suggest improvements. Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242101"></a> <div id="answer-242101" class="answer js-answer" data-answerid="242101" data-score="0" data-position-on-page="25" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242101"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"/></svg> </button> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="0"> 0 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is not useful" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes=""> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewbox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"/></svg> </button> <div class="js-accepted-answer-indicator flex--item fc-green-500 py6 mtn8 d-none" data-s-tooltip-placement="right" title="Loading when this answer was accepted…" tabindex="0" role="note" aria-label="Accepted"> <div class="ta-center"> <svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewbox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8Z"/></svg> </div> </div> <a class="js-post-issue flex--item s-btn s-btn__unset c-pointer py6 mx-auto" href="/web/20220202015155/https://codegolf.stackexchange.com/posts/242101/timeline" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" title="Show activity on this post." aria-label="Timeline"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewbox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"/></svg></a> </div> </div> <div class="answercell post-layout--right"> <span class="d-none">\$\begingroup\$</span> <div class="s-prose js-post-body" itemprop="text"> <h1>T-SQL, 31 bytes</h1> <p>Using bitwise operators</p> <pre class="lang-sql prettyprint-override"><code>PRINT-1/~(@*@b^reverse(@b*~-@)) </code></pre> <p><strong><a href="https://web.archive.org/web/20220202015155/https://dbfiddle.uk/?rdbms=sqlserver_2019&fiddle=9fc7f0105c4dda09629b30cabc563aba" rel="nofollow noreferrer">Try it online</a></strong></p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-01-31T15:47:33"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242101"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242101" rel="nofollow" itemprop="url" class="js-share-link js-gps-track" title="Short permalink to this answer" data-gps-track="post.click({ item: 2, priv: 0, post_type: 2 })" data-controller="se-share-sheet" data-se-share-sheet-title="Share a link to this answer" data-se-share-sheet-subtitle="" data-se-share-sheet-post-type="answer" data-se-share-sheet-social="facebook 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fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-01-31 15:47:33Z" class="relativetime">yesterday</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/53044/t-clausen-dk"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/e0Qyw.jpg?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/53044/t-clausen-dk">t-clausen.dk</a><span class="d-none" itemprop="name">t-clausen.dk</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">3,504</span><span title="8 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">8</span></span><span class="v-visible-sr">8 silver 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Avoid comments like “+1” or “thanks”." href="#" role="button">Add a comment</a> <span class="js-link-separator dno"> | </span> <a class="js-show-link comments-link dno" title="Expand to show all comments on this post" href="#" onclick="" role="button"></a> </div> </div> </div> </div> <a name="242195"></a> <div id="answer-242195" class="answer js-answer" data-answerid="242195" data-score="0" data-position-on-page="26" data-highest-scored="0" data-question-has-accepted-highest-score="0" itemprop="suggestedAnswer" itemscope itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="242195"> <button class="js-vote-up-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" title="This answer is useful" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" 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class="lang-julia prettyprint-override"><code>(a,b,d=digits,s=string)->s(d(a*b))==s(reverse(d(a*b-b))) </code></pre> <p><a href="https://web.archive.org/web/20220202015155/https://tio.run/##Tc5JCsMwDAXQfU@hpV0UkDJn4dKrJGSoS2nASofbuy6lQUs9/v/o@rj5nt9xdtH0OODoRr/4TVCcbMHfF5udxIymPw7WOicmTM8pyPSjLKGNZ7msL5hNjdDZw/8qESoL@1kg5Ny0WlIip6ZT1CDoRE2EwESKyvorrS61nGoVFbqYPiHSoSLntM1KmPal@AE" rel="nofollow noreferrer" title="Julia 1.0 – Try It Online">Try it online!</a></p> <p>Pretty straightforward answer, with nothing particularly clever to it (unfortunately).</p> </div> <div class="mt24"> <div class="d-flex fw-wrap ai-start jc-end gs8 gsy"> <time itemprop="dateCreated" datetime="2022-02-01T23:30:13"></time> <div class="flex--item mr16" style="flex: 1 1 100px;"> <div class="js-post-menu pt2" data-post-id="242195"> <div class="d-flex gs8 s-anchors s-anchors__muted fw-wrap"> <div class="flex--item"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/a/242195" rel="nofollow" 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data-gps-track="post.click({ item: 14, priv: 0, post_type: 2 })" data-controller="s-tooltip " data-s-tooltip-placement="bottom" data-s-popover-placement="bottom" aria-controls="" title="Follow this answer to receive notifications"> Follow </button> </div> </div> <div class="js-menu-popup-container"></div> </div> </div> <div class="post-signature flex--item fl0"> <div class="user-info user-hover"> <div class="user-action-time"> answered <span title="2022-02-01 23:30:13Z" class="relativetime">2 hours ago</span> </div> <div class="user-gravatar32"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/8774/sundar-remember-monica"><div class="gravatar-wrapper-32"><img src="https://web.archive.org/web/20220202015155im_/https://i.stack.imgur.com/RZLo7.png?s=64&g=1" alt="" width="32" height="32" class="bar-sm"></div></a> </div> <div class="user-details" itemprop="author" itemscope itemtype="http://schema.org/Person"> <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/8774/sundar-remember-monica">sundar - Remember Monica</a><span class="d-none" itemprop="name">sundar - Remember Monica</span> <div class="-flair"> <span class="reputation-score" title="reputation score " dir="ltr">5,482</span><span title="15 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">15</span></span><span class="v-visible-sr">15 silver badges</span><span title="29 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">29</span></span><span class="v-visible-sr">29 bronze badges</span> </div> </div> </div> </div> </div> </div> <span class="d-none">\$\endgroup\$</span> </div> <span class="d-none" itemprop="commentCount">2</span> <div class="post-layout--right js-post-comments-component"> <div id="comments-242195" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="242195" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-545757" class="comment js-comment " data-comment-id="545757" data-comment-owner-id="88546" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">33 bytes: <code>a+b="$(a*b)"==reverse("$(a*b-b)")</code>.</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/88546/dingledooper" title="15,735 reputation" class="comment-user">dingledooper</a> </div> <span class="comment-date" dir="ltr"><span title="2022-02-01 23:38:54Z, License: CC BY-SA 4.0" class="relativetime-clean">2 hours ago</span></span> </div> </div> </li> <li id="comment-545758" class="comment js-comment " data-comment-id="545758" data-comment-owner-id="8774" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <div class="comment-body js-comment-edit-hide"> <span class="d-none">\$\begingroup\$</span> <span class="comment-copy">@dingledooper I always forget about the operator trick 🤦 That seems different enough to merit a separate answer!</span> <span class="d-none">\$\endgroup\$</span> <div class="d-inline-flex ai-center"> – <a href="/web/20220202015155/https://codegolf.stackexchange.com/users/8774/sundar-remember-monica" title="5,482 reputation" class="comment-user">sundar - Remember Monica</a> </div> <span class="comment-date" dir="ltr"><span title="2022-02-01 23:43:50Z, License: CC BY-SA 4.0" class="relativetime-clean">2 hours 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