<SCRIPT>
function SumNum(objid1, objid2, objid3) {
>
var b = document.getElementById(objid2).value;
>
{ a = 0 }
>
{ b = 0 }
>
document.getElementById(objid3).value = sumValue;
}
</script>
</head>
<body>
<form>
<asp:TextBox id="ID1" runat="server" onkeyup="value=value.replace(/[^\d\.]/g,'');SumNum('ID1','ID2','ID3');"></asp:TextBox>
<asp:TextBox>
<asp:TextBox id="ID3" runat="server" ></asp:TextBox>
</form>
</body>