Name the place. Compare the distances.

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Compare the distances.</title><style>:root{--paper:#f5f7fb;--ink:#23344d;--accent:#375a91;--line:#c7d3e5;--panel:#fff;--soft:#e8eef8}*{box-sizing:border-box}:root{color-scheme:light}body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.65 system-ui,-apple-system,"Segoe UI",sans-serif}main{max-width:960px;margin:auto;padding:28px 24px 54px}.strap{font-weight:750;letter-spacing:.07em;font-size:16px;color:var(--accent)}header{padding:20px 0 24px;border-top:7px solid var(--accent);border-bottom:2px solid var(--line);margin-bottom:24px}h1{font:700 clamp(30px,5vw,45px)/1.2 Georgia,serif;margin:10px 0 18px;max-width:780px}h2{font:700 25px/1.35 Georgia,serif;margin:0 0 16px}h3{font-size:19px;margin:18px 0 10px}p{margin:12px 0}section{margin:24px 0;padding:22px;background:var(--panel);border:1px solid var(--line);border-radius:8px;min-width:0}.plain section{border-radius:0;border-width:0 0 2px;padding:24px 0;background:transparent}.studio header{border-top-style:double;border-top-width:10px}.studio section{box-shadow:5px 5px 0 var(--line)}.board section{border-top:5px solid var(--accent)}.metric{font-size:clamp(26px,5vw,38px);font-weight:750;line-height:1.3}.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.three{grid-template-columns:repeat(3,minmax(0,1fr))}.cell{padding:16px;background:var(--panel);border-left:4px solid var(--accent);min-width:0}.choices,.toolbar{display:flex;flex-wrap:wrap;gap:10px;margin:12px 0 18px}button,input,textarea{font:inherit}button{padding:11px 16px;min-height:46px;border:1px solid var(--accent);border-radius:6px;background:var(--panel);color:var(--accent);cursor:pointer;max-width:100%;line-height:1.4}button:hover{box-shadow:0 0 0 2px var(--line)}button[aria-pressed=true],button.primary{background:var(--accent);color:#fff}button:focus-visible,input:focus-visible,textarea:focus-visible{outline:3px solid #a25718;outline-offset:3px}label,legend{font-weight:650;display:block;margin:12px 0 7px}fieldset{border:0;padding:0;margin:16px 0;min-width:0}input,textarea{border:1px solid #6a7c7d;background:#fff;color:#182f32;padding:11px;width:100%;min-width:0;border-radius:5px}textarea{resize:vertical}.feedback{padding:16px;border-left:4px solid var(--accent);background:var(--soft);margin:18px 0;white-space:pre-line;overflow-wrap:anywhere}.note{border-left:4px solid var(--accent);padding:12px 16px;background:var(--soft)}table{width:100%;border-collapse:collapse;table-layout:fixed;font-size:16px}th,td{text-align:left;vertical-align:top;padding:11px 8px;border-bottom:1px solid var(--line);overflow-wrap:anywhere}th{background:var(--soft)}svg{display:block;width:100%;height:auto;max-width:540px;margin:16px auto;background:#fff}svg text{font:24px system-ui;fill:var(--ink)}footer{border-top:2px solid var(--line);margin-top:30px;padding-top:18px;font-size:16px}[hidden]{display:none!important}.sentence{font:26px/1.7 Georgia,serif;padding:16px;background:var(--soft)}.map-node{border:2px solid var(--accent);padding:16px;text-align:center;font-size:23px;background:var(--panel);max-width:460px;margin:auto}.map-link{text-align:center;padding:10px;font-weight:700}.lane{padding:18px;border:2px dashed var(--line)}@media(max-width:640px){main{padding:20px 16px 40px}.grid,.three{grid-template-columns:1fr}section{padding:18px 14px}.studio section{box-shadow:3px 3px 0 var(--line)}th,td{padding:9px 5px}}</style></head><body class="plain"><main><header><div class="strap">ORIGINAL WORKED EXAMPLE</div><h1>Name the place. Compare the distances.</h1><p>Three original rounding cards. Whole integers 0–999; nearest ten or hundred. Nonnegative halfway cases round upward.</p></header><fieldset><legend>Choose a supplied card</legend><div class="choices"><button type="button" id="card-R1" aria-pressed="false">R1 / 347 to ten</button><button type="button" id="card-R2" aria-pressed="false">R2 / 347 to hundred</button><button type="button" id="card-R3" aria-pressed="false">R3 / 345 to ten</button></div></fieldset><div class="grid"><div><label for="original">Original whole number</label><input id="original" type="text" aria-label="Original whole number" value="347" autocomplete="off"><fieldset><legend>Target place</legend><div class="choices"><button type="button" id="place-10" aria-pressed="false">Nearest ten</button><button type="button" id="place-100" aria-pressed="false">Nearest hundred</button></div></fieldset><p id="round-label" class="note"></p></div><div id="number-line"><p>Attempt the neighbors and distances before checking.</p></div></div><section ><h2>Your prediction</h2><div class="grid"><div><label for="lower">Lower neighboring multiple</label><input id="lower" type="text" aria-label="Lower neighboring multiple" value="" autocomplete="off"></div><div><label for="upper">Upper neighboring multiple</label><input id="upper" type="text" aria-label="Upper neighboring multiple" value="" autocomplete="off"></div><div><label for="distance-low">Distance to lower</label><input id="distance-low" type="text" aria-label="Distance to lower" value="" autocomplete="off"></div><div><label for="distance-high">Distance to upper</label><input id="distance-high" type="text" aria-label="Distance to upper" value="" autocomplete="off"></div><div><label for="prediction">Rounded prediction</label><input id="prediction" type="text" aria-label="Rounded prediction" value="" autocomplete="off"></div></div><label for="round-reason">Explain the closer distance or midpoint rule</label><textarea id="round-reason" rows="3"></textarea><div class="toolbar"><button type="button" id="check" >Check prediction</button><button type="button" id="reset" >Reset</button></div><div id="round-feedback" class="feedback" role="status" aria-live="polite">Not checked yet.</div></section><footer>Local review only. Entries and changes stay in this open page; reload restores the example. Keep actual records in the required native document or workflow.</footer></main><script>
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let currentCard='R1',place=10;const fields=["lower","upper","distance-low","distance-high","prediction"];function clear(){blank([...fields,'round-reason']);put('round-feedback','Not checked. Enter neighbors, distances, prediction, and a reason.');$('number-line').innerHTML='<p>Attempt the neighbors and distances before checking.</p>';put('round-label',currentCard+' / original '+$('original').value+' / nearest '+place);}const places=pick('place',['10','100'],v=>{place=Number(v);clear();});const cards=pick('card',['R1','R2','R3'],v=>{currentCard=v;$('original').value=v==='R3'?'345':'347';place=v==='R2'?100:10;places.set(String(place));clear();});cards.set('R1');places.set('10');edit(['original'],clear);edit([...fields,'round-reason'],()=>{put('round-feedback','Prediction changed. Check again.');$('number-line').innerHTML='<p>Complete the attempt before the number line is shown.</p>';});on('check',()=>{try{const n=number('original',0,999,true);const values=fields.map(id=>number(id,0,1000,true));if(!$('round-reason').value.trim())throw Error('Add a short reason before checking the numeric key.');const low=Math.floor(n/place)*place,high=low+place,dl=n-low,dh=high-n,answer=dl<dh?low:high;const expected=[low,high,dl,dh,answer];const matches=values.every((v,i)=>v===expected[i]);put('round-feedback',(matches?'Matching numeric prediction. ':'Recheck the numeric record. ')+'Neighbors '+low+' and '+high+'; distances '+dl+' and '+dh+'; rounded '+answer+'. '+(dl===dh?'Equal distances: use the stated nonnegative half-up rule.':'Choose the smaller distance; an exact multiple stays unchanged.')+' Teacher reviews the reason.');const px=50+300*dl/place;$('number-line').innerHTML='<svg viewBox="0 0 400 160" role="img" aria-label="Number line for current rounding interval"><title>Neighbors '+low+' and '+high+', original '+n+'</title><path d="M50 80H350 M50 70V90 M350 70V90" stroke="#375a91" stroke-width="3"/><circle cx="'+px+'" cy="80" r="6" fill="#83511d"/><text x="50" y="120" text-anchor="middle">'+low+'</text><text x="350" y="120" text-anchor="middle">'+high+'</text><text x="'+px+'" y="50" text-anchor="middle">'+n+'</text></svg><p>Distances: '+dl+' to lower, '+dh+' to upper. Equal drawing units.</p>';}catch(e){put('round-feedback',e.message);$('number-line').innerHTML='<p>Complete the attempt before the number line is shown.</p>';}});on('reset',()=>{currentCard='R1';place=10;$('original').value='347';places.set('10');cards.set('R1');clear();});clear();
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