限定输入数字问题
怎样在下面代吗中input中限定输入数字啊?不是高手不要答哦
<%
dim t1,t2,r1,result
if request("action")="chk" then
t1=cint(request("t1"))
t2=cint(request("t2"))
r1=request("r1")
if r1="V1" then
result=t1+t2
end if
if r1="V2" then
result=t1-t2
end if
if r1="V3" then
result=t1*t2
end if
if r1="V4" then
result=t1/t2
end if
response.write "结果为: "
response.write result
else
%>
<html>
<head>
<meta http-equiv="Content-Language" content="zh-cn">
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<meta name="GENERATOR" content="Microsoft FrontPage 6.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<title>算术运算</title>
</head>
<body>
<p>
<br><br>
</p>
<form method="GET" action="func.asp">
<table border="0" width="100%">
<tr>
<td width="7%"></td>
<td width="79%" align="center"><input type="text" name="T1" size="20"></td>
<td width="14%"></td>
</tr>
<tr>
<td width="7%"></td>
<td width="79%" align="center">
<table border="1" width="27%" cellspacing="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#008080">
<tr>
<td width="53%" align="center"><input type="radio" value="V1" checked name="R1"></td>
<td width="147%" align="center">加</td>
</tr>
<tr>
<td width="53%" align="center"><input type="radio" value="V2" checked name="R1"></td>
<td width="147%" align="center">减</td>
</tr>
<tr>
<td width="53%" align="center"><input type="radio" value="V3" checked name="R1"></td>
<td width="147%" align="center">乘</td>
</tr>
<tr>
<td width="53%" align="center"><input type="radio" value="V4" checked name="R1"></td>
<td width="147%" align="center">除</td>
</tr>
</table>
</td>
<td width="14%"></td>
</tr>
<tr>
<td width="7%"></td>
<td width="79%" align="center"><input type="text" name="T2" size="20"></td>
<td width="14%"></td>
</tr>
<tr>
<td width="7%"></td>
<td width="79%" align="center"></td>
<td width="14%"></td>
</tr>
<tr>
<td width="7%"><INPUT TYPE="hidden" value="chk" name="action"></td>
<td width="79%" align="center"><input type="submit" value="提 交" name="B1">
<input type="reset" value="重 写" name="B2"></td>
<td width="14%"></td>
</tr>
</table>
</form>
</body>
</html>
<%end if
%>