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<!DOCTYPE html>
<html data-require="math word-problems math-format expressions">
<head>
<meta charset="UTF-8" />
<title>Place value</title>
<script src="../khan-exercise.js"></script>
</head>
<body>
<div class="exercise">
<div class="problems">
<div>
<div class="vars">
<var id="DIGITS">shuffle([1, 2, 3, 4, 5, 6, 7, 8, 9]).slice( 0, 4 )</var>
<var id="NUMBER">digitsToInteger( DIGITS )</var>
<var id="POWER">randRange( 0, 3 )</var>
<var id="DIGIT">DIGITS[POWER]</var>
<var id="HINT_IN_NUMBERS">
(function() {
var maxPower = DIGITS.length - 1;
var products = jQuery.map( DIGITS, function( digit, index ){
return expr([ "*", digit, pow( 10, maxPower - index ) ]);
});
return products.join( "+" );
})()
</var>
<var id="HINT_IN_WORDS">
(function() {
var maxPower = DIGITS.length - 1;
var words = jQuery.map( DIGITS, function( digit, index ) {
return plural( digit, powerToPlace( maxPower - index ) );
});
return words.join( " + " );
})()
</var>
<var id="PLACES">
(function() {
var places = placesLeftOfDecimal.slice( 0, 4 );
return jQuery.map( places, function( place, i ) {
return place + "s";
});
})()
</var>
<var id="SOLUTION">PLACES[ DIGITS.length - 1 - POWER ]</var>
</div>
<p class="question">What is the place value of <var>DIGIT</var> in <var>NUMBER</var>?</p>
<p class="solution"><var>SOLUTION</var></p>
<ul class="choices" data-category="true">
<li data-each="PLACES as place"><var>place</var></li>
</ul>
<div class="hints">
<div>
<p><var>NUMBER</var> can be represented as follows.</p>
<p><code>= <var>HINT_IN_NUMBERS</var></code></p>
</div>
<p><code>= </code> <var>HINT_IN_WORDS</var></p>
<p class="final_hint">Thus, <var>DIGIT</var> is in the <var>SOLUTION</var> place.</p>
</div>
</div>
<div>
<div class="vars" data-ensure="NUMBER > 99">
<var id="DIGITS">randRange( 0, 9, 4 )</var>
<var id="NUMBER">digitsToInteger( DIGITS )</var>
<var id="ADDENDS">[ ]</var>
<var id="HINT">
(function() {
var maxPower = DIGITS.length - 1;
return jQuery.map(DIGITS, function(digit, index) {
if ( digit === 0 ) {
return null;
}
if ( index === DIGITS.length - 1 ) {
if ( DIGITS[ index - 1] === 0 ) {
ADDENDS.push( digit );
return cardinal( digit ) + " is the same as " + digit;
}
} else if ( index === DIGITS.length - 2 ) {
var addend = digit * 10 + DIGITS[ DIGITS.length - 1 ];
ADDENDS.push( addend );
return cardinal( addend ) + " is the same as " + addend;
} else {
var words = cardinal( digit ) + " " + powerToPlace(maxPower - index);
var input = [ "*", digit, pow(10, maxPower - index) ];
var ex = expr( input );
var addend = expr( input, true );
ADDENDS.push( addend );
return words + " is the same as " + ex + " = " + addend;
}
});
})()
</var>
</div>
<p class="question">What is <var>cardinal( NUMBER )</var> in standard form?</p>
<p class="solution"><var>NUMBER</var></p>
<div class="hints">
<p data-each="HINT as hint"><var>hint</var></p>
<div>
<p>Add all these parts up:</p>
<p><var>ADDENDS.join( " + " )</var></p>
</div>
<p>= <var>NUMBER</var></p>
</div>
</div>
</div>
</div>
</body>
</html>
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