Hexadecimal → octal

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<html lang="en-US"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>Hexadecimal → octal</title><style>*{box-sizing:border-box}body{margin:0;background:#f3f4f2;color:#202c32;font:16px/1.5 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}main{max-width:1120px;margin:auto;padding:30px 28px 60px}header{margin-bottom:22px}.eyebrow{font-size:12px;letter-spacing:.14em;text-transform:uppercase;font-weight:750;color:#59676b}h1{font-size:clamp(25px,4vw,36px);line-height:1.15;letter-spacing:-.035em;margin:7px 0 10px}h2{font-size:21px;line-height:1.3;margin:0 0 16px}h3{font-size:17px;margin:0 0 10px}p{margin:8px 0 16px}label{display:block;font-size:14px;font-weight:650;margin:12px 0 5px}input,select,textarea,button{font:inherit}input,select,textarea{width:100%;min-width:0;border:1px solid #b6c0bf;border-radius:7px;background:#fff;color:#202c32;padding:10px 12px}textarea{resize:vertical;min-height:88px}input[type=checkbox]{width:18px;height:18px;vertical-align:middle;margin-right:8px}button{border:1px solid #b8c3c1;border-radius:7px;padding:10px 15px;background:#fff;color:#203632;font-weight:650;cursor:pointer}button.primary{background:#243f3c;color:white;border-color:#243f3c}button:hover{filter:brightness(.95)}button:disabled{opacity:.48;cursor:not-allowed}:focus-visible{outline:3px solid #b05814;outline-offset:3px}.buttons{display:flex;gap:8px;flex-wrap:wrap;margin-top:18px}.panel{background:#fff;border:1px solid #d7ddda;border-radius:12px;padding:24px}.split{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.1fr);gap:22px}.row{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.result{background:#e4eee8;border:1px solid #c5d6ca;border-radius:12px;padding:28px}.big{font-size:clamp(32px,5vw,56px);font-weight:740;line-height:1.14;letter-spacing:-.04em;overflow-wrap:anywhere;font-variant-numeric:tabular-nums}.muted{color:#59686a;font-size:14px}.tag{display:inline-block;background:#edf0ed;border-radius:4px;padding:3px 8px;font-size:12px;font-weight:700}.error{color:#9d301b;font-weight:650;min-height:24px;margin-top:10px}.note{border-left:3px solid #9a794a;padding:10px 15px;background:#faf5e9;margin:18px 0}.below{margin-top:28px}.record{white-space:pre-wrap;overflow-wrap:anywhere;font:14px/1.65 ui-monospace,SFMono-Regular,Consolas,monospace;background:#f2f4f1;padding:18px;border-radius:8px}table{width:100%;border-collapse:collapse;font-size:14px}th,td{text-align:left;vertical-align:top;border-bottom:1px solid #dce1dd;padding:12px 10px;overflow-wrap:anywhere}th{color:#59686a;font-size:12px}a{color:#2c5a6a;overflow-wrap:anywhere}details{margin-top:20px}summary{cursor:pointer;font-weight:650}hr{border:0;border-top:1px solid #d6dcd6;margin:22px 0}[hidden]{display:none!important}ol,ul{padding-left:23px}.statline{display:flex;gap:20px;flex-wrap:wrap;margin:18px 0}.statline strong{display:block;font-size:24px}.inline{display:flex;align-items:center;gap:8px}.inline label{margin:0} .blank{min-height:36px;border-bottom:1px dashed #aebbb5;color:#66736d;font-size:13px;padding:8px 0}@media(max-width:720px){main{padding:22px 18px 45px}.split{grid-template-columns:1fr}.panel,.result{padding:20px}.row{gap:12px}th,td{padding:10px 6px}}@media(max-width:400px){main{padding:18px 14px 40px}.big{font-size:34px}button{padding:10px 12px}.row{grid-template-columns:1fr}.panel,.result{padding:17px}}.inline{flex-wrap:wrap}input[type=range]{padding:0}pre{white-space:pre-wrap;overflow-wrap:anywhere;margin:0}.metric{font-size:42px;font-weight:750;line-height:1.15;letter-spacing:-.035em}.caption{font-size:13px;color:#55656b}.readout{font:15px/1.6 ui-monospace,Consolas,monospace;white-space:pre-wrap;overflow-wrap:anywhere}.strip{display:flex;gap:24px;align-items:center;flex-wrap:wrap}.chip{padding:5px 10px;background:#e5eaf0;border-radius:5px;font-size:13px}button[aria-pressed=true]{background:#263b50;color:white}.subtle{background:#f6f7f7}.fileCode{min-height:230px;font:14px/1.6 ui-monospace,Consolas,monospace}.wideButton{width:100%}.visuallyHidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}svg{max-width:100%}.nowrap{white-space:nowrap}.conversion{display:grid;grid-template-columns:1.2fr 1fr;gap:24px}.conversion .result{background:#e4eaf0;border-color:#c5d1de}.conversion input{font-family:ui-monospace,Consolas,monospace}.conversion .big{font-family:ui-monospace,Consolas,monospace;font-size:clamp(40px,6vw,76px)}@media(max-width:720px){.conversion{grid-template-columns:1fr}}</style></head><body><main><header><div class="eyebrow">Integer representation inspector</div><h1>Hexadecimal → octal</h1></header>
<section class="conversion"><div class="result"><span class="eyebrow">Canonical output · base <span id="targetBase">8</span></span><div class="big" id="answer">52</div><p id="identity">2A hexadecimal = 42 decimal = 52 octal</p><div id="place" class="readout">2 × 16¹ + 10 × 16⁰ = 42<br>5 × 8¹ + 2 × 8⁰ = 42</div></div><form class="panel" id="form" novalidate><label for="token">Original source token</label><input id="token" value="2A" autocomplete="off" spellcheck="false"><div class="row"><div><label for="from">Source base</label><select id="from"><option value="8">8 · Octal</option><option value="10">10 · Decimal</option><option value="16" selected>16 · Hexadecimal</option></select></div><div><label for="to">Destination base</label><select id="to"><option value="8" selected>8 · Octal</option><option value="10">10 · Decimal</option><option value="16">16 · Hexadecimal</option></select></div></div><div class="buttons"><button type="submit" class="primary">Convert whole token</button><button type="button" id="reset">Reset</button></div><p class="error" role="status" id="feedback"></p></form></section>
<section class="panel below"><h2>Base-labeled conversion record</h2><pre id="record" class="record"></pre><p class="muted">Bare unsigned digits only; leading zeros are allowed. Exact supported range: 0–9007199254740991. Signs, prefixes, fractions and separators are outside this inspector. E is a valid hexadecimal digit, not exponent syntax.</p><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toString">MDN: radix formatting</a> · <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt">Why prefix parsing is insufficient</a></section><footer class="muted below">Local working copy · Changes are not saved after this page closes.</footer></main><script data-app>
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const names={8:'octal',10:'decimal',16:'hexadecimal'},alphabets={8:/^[0-7]+$/,10:/^[0-9]+$/,16:/^[0-9A-Fa-f]+$/};
function convert(raw,from,to){if(!Object.hasOwn(alphabets,from)||!Object.hasOwn(alphabets,to))throw Error('Choose a supported source and destination base.');const token=raw.trim();if(!alphabets[from].test(token))throw Error('The whole token must use base '+from+' digits only.');let value=0;for(const ch of token.toUpperCase()){const d='0123456789ABCDEF'.indexOf(ch);if(value>Math.floor((Number.MAX_SAFE_INTEGER-d)/Number(from)))throw Error('Outside the exact supported range: 0–9007199254740991.');value=value*Number(from)+d}return {raw,token,from,to,value,output:value.toString(Number(to)).toUpperCase()}}
function expansion(token,base){const s=token.toUpperCase().replace(/^0+(?=.)/,'');const powers=['⁰','¹','²','³','⁴','⁵','⁶','⁷','⁸','⁹'];return [...s].map((ch,i)=>'0123456789ABCDEF'.indexOf(ch)+' × '+base+(powers[s.length-i-1]||'^'+(s.length-i-1))).join(' + ')}
function clear(){['answer','identity','place','record'].forEach(id=>text(id,'—'));text('feedback','Input changed. Convert to update.');text('targetBase',$('to').value||'—')}
function calculate(){clear();try{const r=convert($('token').value,$('from').value,$('to').value);text('answer',r.output);text('identity',r.token+' '+names[r.from]+' = '+r.value+' decimal = '+r.output+' '+names[r.to]);text('place',expansion(r.token,r.from)+' = '+r.value+'\n'+expansion(r.output,r.to)+' = '+r.value);text('record','Original token: '+JSON.stringify(r.raw)+'\nValidated token: '+r.token+'\nSource: base '+r.from+' ('+names[r.from]+')\nExact decimal value: '+r.value+'\nDestination: base '+r.to+' ('+names[r.to]+')\nCanonical output: '+r.output);text('feedback','Whole token validated; exact integer conversion.')}catch(e){text('feedback',e.message)}}
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