​x
 
<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 数字</h1>
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<p>浮点的算数并不总是 100% 精准：</p>
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<p id="demo1"></p>
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<p>但是乘法和除法是有用的：</p>
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<p id="demo2"></p>
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<script>
var x = 0.2 + 0.1;
document.getElementById("demo1").innerHTML = "0.2 + 0.1 = " + x;
var y = (0.2*10 + 0.1*10) / 10;
document.getElementById("demo2").innerHTML = "0.2 + 0.1 = " + y;
</script>
​
</body>
</html>
​