<!-- 把如下代码加入<body>区域中 -->
<script language="JavaScript">
<!-- Hide the script from old browsers --
function compute(obj)
{obj.expr.value = eval(obj.expr.value)}
var one = '1'
var two = '2'
var three = '3'
var four = '4'
var five = '5'
var six = '6'
var seven = '7'
var eight = '8'
var nine = '9'
var zero = '0'
var plus = '+'
var minus = '-'
var multiply = '*'
var divide = '/'
var decimal = '.'
function enter(obj, string)
{obj.expr.value += string}
function clear(obj)
{obj.expr.value = ''}
// --End Hiding Here -->
</script>
<form name="calc">
<table border=1>
<td colspan=4><input type="text" name="expr" size=30 action="compute(this.form)"> <tr>
<td><input type="button" value=" 7 " onClick="enter(this.form, seven)">
<td><input type="button" value=" 8 " onClick="enter(this.form, eight)">
<td><input type="button" value=" 9 " onClick="enter(this.form, nine)">
<td><input type="button" value=" / " onClick="enter(this.form, divide)">
<tr><td><input type="button" value=" 4 " onClick="enter(this.form, four)">
<td><input type="button" value=" 5 " onClick="enter(this.form, five)">
<td><input type="button" value=" 6 " onClick="enter(this.form, six)">
<td><input type="button" value=" * " onClick="enter(this.form, multiply)">
<tr><td><input type="button" value=" 1 " onClick="enter(this.form, one)">
<td><input type="button" value=" 2 " onClick="enter(this.form, two)">
<td><input type="button" value=" 3 " onClick="enter(this.form, three)">
<td><input type="button" value=" - " onClick="enter(this.form, minus)">
<tr><td colspan=2><input type="button" value=" 0 " onClick="enter(this.form, zero)">
<td><input type="button" value=" . " onClick="enter(this.form, decimal)">
<td><input type="button" value=" + " onClick="enter(this.form, plus)">
<tr><td colspan=2><input type="button" value=" = " onClick="compute(this.form)">
<td colspan=2><input type="button" value="AC" size= 3 onClick="clear(this.form)"> </table>
</form>