<!DOCTYPE html>
<html>
<body>
<script>
var x;
document.write("<p>只有 17 位: ");
x=12345678901234567890;
document.write(x + "</p>");
document.write("<p>0.2 + 0.1 = ");
x=0.2+0.1;
document.write("<p>可分别乘以 10 并除以 10 : ");
x=(0.2*10+0.1*10)/10;
document.write(x +"</p>");
</script>
</body>
</html>