Fraction Calculator Website: Keep the Exact Answer

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<html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>Fraction Calculator Website: Keep the Exact Answer</title><style>*{box-sizing:border-box}body{margin:0;color:var(--ink,#233342);background:var(--bg,#eef2f3);font:17px/1.6 system-ui,sans-serif}main{max-width:980px;margin:auto;padding:clamp(16px,4vw,38px)}h1{font:700 clamp(30px,5vw,49px)/1.12 Georgia,serif;margin:10px 0 20px;max-width:800px}h2{font-size:24px;line-height:1.3;margin:0 0 15px}h3{font-size:19px;margin:12px 0}p{margin:0 0 16px}.eyebrow{font-weight:750;letter-spacing:.08em;text-transform:uppercase;font-size:16px}header{padding:10px 0 25px;border-bottom:3px solid var(--accent,#24586d);margin-bottom:24px}.lede{font-size:20px;max-width:760px}.panel{background:var(--paper,#fff);padding:clamp(18px,3vw,28px);border:1px solid var(--line,#c6d1d8);border-radius:12px;margin:20px 0}.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.grid>*{min-width:0}.row{display:flex;gap:12px;flex-wrap:wrap;align-items:center;margin:16px 0}.stack>*{margin:12px 0}button{font:700 17px/1.4 system-ui,sans-serif;cursor:pointer;color:white;background:var(--accent,#24586d);border:2px solid var(--accent,#24586d);border-radius:7px;padding:11px 17px;max-width:100%;overflow-wrap:anywhere}button.secondary{background:transparent;color:var(--ink,#233342)}button[aria-pressed=true]{box-shadow:inset 0 0 0 3px #fff;outline:2px solid var(--ink,#233342)}button:disabled{opacity:.55;cursor:default}input,textarea,select{font:17px/1.5 system-ui,sans-serif;color:inherit;background:white;border:1px solid #778591;padding:10px 12px;border-radius:6px;max-width:100%;width:100%;min-width:0}input[type=checkbox]{width:22px;height:22px}textarea{min-height:110px;resize:vertical}label{display:block;font-weight:700;margin:12px 0 7px}button:focus-visible,input:focus-visible,textarea:focus-visible,summary:focus-visible,[tabindex]:focus-visible{outline:3px solid #aa3d70;outline-offset:4px}.result{padding:18px;border-left:5px solid var(--accent,#24586d);background:var(--soft,#e5eff2);white-space:pre-wrap;overflow-wrap:anywhere;margin:20px 0}.result:empty{display:none}.hint{font-size:16px;color:var(--muted,#435968)}table{border-collapse:collapse;width:100%;table-layout:fixed;margin:16px 0}th,td{text-align:left;vertical-align:top;overflow-wrap:anywhere;padding:12px 8px;border-bottom:1px solid var(--line,#c6d1d8)}caption{text-align:left;font-weight:750;margin:8px 0}details{padding:18px;border:1px dashed #7b8b96;margin:20px 0}summary{cursor:pointer;font-weight:750}pre{font:16px/1.6 ui-monospace,monospace;white-space:pre-wrap;overflow-wrap:anywhere;background:#162735;color:#f5f8fa;padding:18px;border-radius:8px}canvas,svg{display:block;max-width:100%;height:auto}footer{margin:28px 0;font-size:16px}.badge{font-weight:750;color:var(--accent,#24586d)}.metric{font:700 38px/1.3 Georgia,serif}.board{display:grid;gap:5px;max-width:440px;margin:20px auto}.board button{padding:7px;min-height:45px}.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}@media(max-width:560px){.grid{grid-template-columns:1fr}main{padding:16px}th,td{padding:10px 5px}.row button{flex-grow:1}.metric{font-size:32px}}
:root{--bg:#edf0f5;--paper:#fff;--accent:#4d4d8f;--soft:#e9e8f6;--ink:#30314d}.fraction{display:grid;grid-template-columns:1fr;max-width:210px;margin:auto}.fraction input{text-align:center;font-size:25px}.fraction input:first-of-type{border-bottom:3px solid #4d4d8f}.exact{font:700 36px Georgia,serif}</style></head><body><main><header><p class="eyebrow">Rational workbench · Four integers</p><h1>Fraction Calculator Website: Keep the Exact Answer</h1><p class="lede">Choose the operation, inspect its raw fraction, then reduce by the greatest common divisor.</p><p class="hint">Exact two-operand arithmetic within ±10,000 per integer field. No expression parser or saved calculation history.</p></header><section class="panel"><div class="grid"><div class="fraction"><h2>First fraction</h2><label for="a">Numerator a</label><input id="a" value="3" inputmode="numeric"><label for="b">Denominator b</label><input id="b" value="4" inputmode="numeric"></div><div class="fraction"><h2>Second fraction</h2><label for="c">Numerator c</label><input id="c" value="1" inputmode="numeric"><label for="d">Denominator d</label><input id="d" value="6" inputmode="numeric"></div></div><div class="row" role="group" aria-label="Operation"><button id="add" type="button" aria-pressed="true">Add</button><button id="sub" type="button" aria-pressed="false">Subtract</button><button id="mul" type="button" aria-pressed="false">Multiply</button><button id="div" type="button" aria-pressed="false">Divide</button></div><div class="row"><button id="calculate" type="button">Calculate</button><button id="reset" type="button" class="secondary">Reset</button></div><p id="exact" class="exact" role="status"></p><p id="trace" class="result"></p></section><section class="panel"><h2>Original positive-addition illustration</h2><p>3/4 = 9/12; 1/6 = 2/12; together 11/12.</p><div aria-label="Eleven of twelve equal cells filled" style="display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:2px"><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#7774b1;border:1px solid #535079"></span><span style="height:28px;background:#e7e7ef;border:1px solid #535079"></span></div><p class="hint">This strip illustrates the default addition only. Signed and improper results use the calculation trace.</p></section><footer>Keep any records you need in your own working files. This page makes no network requests and saves no responses.</footer></main><script>
(()=>{'use strict';const $=id=>document.getElementById(id);
let op='add';const names={add:'Add',sub:'Subtract',mul:'Multiply',div:'Divide'};function clear(){$('exact').textContent='';$('trace').textContent='';}for(const k of ['a','b','c','d'])$(k).addEventListener('input',clear);for(const k of Object.keys(names))$(k).addEventListener('click',()=>{op=k;for(const x of Object.keys(names))$(x).setAttribute('aria-pressed',String(x===op));clear();});function gcd(a,b){while(b){const t=a%b;a=b;b=t;}return a;}function calc(){clear();const raw=['a','b','c','d'].map(k=>$(k).value.trim());if(!op||raw.some(x=>! /^[+-]?\d+$/.test(x)||Math.abs(Number(x))>10000)){$('exact').textContent='Choose an operation and enter four signed integers within ±10000.';return;}let[a,b,c,d]=raw.map(Number);if(b===0||d===0){$('exact').textContent='A denominator cannot be zero.';return;}let normalization='';if(b<0){a=-a;b=-b;normalization+='First denominator normalized positive. ';}if(d<0){c=-c;d=-d;normalization+='Second denominator normalized positive. ';}if(op==='div'&&c===0){$('exact').textContent='Cannot divide by a zero fraction.';return;}let n,z,rule;if(op==='add'||op==='sub'){n=a*d+(op==='add'?1:-1)*b*c;z=b*d;rule=a*d+'/'+z+(op==='add'?' + ':' − ')+b*c+'/'+z;}else if(op==='mul'){n=a*c;z=b*d;rule=a+'/'+b+' × '+c+'/'+d;}else{n=a*d;z=b*c;rule=a+'/'+b+' × reciprocal '+d+'/'+c;}if(z<0){n=-n;z=-z;}if(!Number.isSafeInteger(n)||!Number.isSafeInteger(z)){ $('exact').textContent='Integer intermediate out of bounds.';return;}const g=gcd(Math.abs(n),z),rn=n===0?0:n/g,rd=n===0?1:z/g;$('exact').textContent='Exact result: '+rn+'/'+rd;$('trace').textContent=normalization+'Normalized operands: '+a+'/'+b+' and '+c+'/'+d+'.\n'+names[op]+': '+rule+' = '+n+'/'+z+'.\ngcd('+Math.abs(n)+','+z+') = '+g+'. Reduced: '+rn+'/'+rd+'.';}$('calculate').addEventListener('click',calc);$('reset').addEventListener('click',()=>{for(const k of ['a','b','c','d'])$(k).value='';op='';for(const k of Object.keys(names))$(k).setAttribute('aria-pressed','false');clear();});
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