<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Math的常用方法1</title>
<script type="text/javascript">
var n=-10;
console.log(Math.abs(n));//10
console.log(Math.pow(n,2));//100
console.log(Math.sqrt(25));//5
//3次方根：8的1/3次方
console.log(Math.pow(8,1/3));
var ret=Math.sin(Math.PI/6)
console.log(ret.toFixed(3));//保留小数点后尾数，返回string
</script>
</head>
<body>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Math的常用方法2</title>
<script type="text/javascript">
var n=prompt("pls input:")*1;
var ret=Math.floor(n);
console.log("floor:"+ret);
ret=Math.ceil(n);
console.log("ceil:"+ret);
ret=Math.round(n);
console.log("round:"+ret);
</script>
</head>
<body>
</body>
</html>
原文：http://www.cnblogs.com/xinxinxinxin/p/6673512.html