<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<script>
function aa() {
var a = Number($("#txt1").val());
var b = Number($("#txt2").val());
var c = Number($("#txt3").val());
alert(Number((a + b).toFixed(2)));//结果：13.4
alert((a + b) == c);//结果：false
alert(Number((a + b).toFixed(2)) == Number(c.toFixed(2)));//结果：true
}
</script>
<script src="Js/jquery-1.8.3.min.js"></script>
</head>
<body>
<form id="form1" runat="server">
<div>
<input id="txt1" type="text" value="9.2" />
<input id="txt2" type="text" value="4.2" />
<input id="txt3" type="text" value="13.4" />
<input id="Button1" type="button" onclick="aa();" value="button" />
</div>
</form>
</body>
</html>