<html>
<head>
<meta charset="utf-8"/>
<scripttype="text/javascript">
varflag = true;
functiongetNum(num){
if(!flag){
document.getElementById('res').value= '';
flag= true;
}
document.getElementById('res').value+= num;
}
functiongetRes(){
varnum = document.getElementById('res').value;
num= eval(num);
document.getElementById('res').value= num;
flag= false;
}
</script>
</head>
<body>
<TABLE border="1px"width="300px">
<caption>简易计算器</caption>
<TR>
<TDcolspan="4"><input type="text" id="res"size="44"/></TD>
</TR>
<TR>
<TD><inputtype="button" value="1" style="width:75px"onclick="getNum(1)"/></TD>
<TD><inputtype="button" value="2" style="width:75px"onclick="getNum(2)"/></TD>
<TD><inputtype="button" value="3" style="width:75px"onclick="getNum(3)"/></TD>
<TD><inputtype="button" value="+" style="width:75px"onclick="getNum('+')"/></TD>
</TR>
<TR>
<TD><inputtype="button" value="4" style="width:75px"onclick="getNum(4)"/></TD>
<TD><inputtype="button" value="5" style="width:75px"onclick="getNum(5)"/></TD>
<TD><inputtype="button" value="6" style="width:75px"onclick="getNum(6)"/></TD>
<TD><inputtype="button" value="-" style="width:75px"onclick="getNum('-')"/></TD>
</TR>
<TR>
<TD><inputtype="button" value="7" style="width:75px"onclick="getNum(7)"/></TD>
<TD><inputtype="button" value="8" style="width:75px"onclick="getNum(8)"/></TD>
<TD><inputtype="button" value="9" style="width:75px"onclick="getNum(9)"/></TD>
<TD><inputtype="button" value="*" style="width:75px"onclick="getNum('*')"/></TD>
</TR>
<TR>
<TD><inputtype="button" value="0" style="width:75px"onclick="getNum(0)"/></TD>
<TD><inputtype="button" value="." style="width:75px"onclick="getNum('.')"/></TD>
<TD><inputtype="button" value="=" style="width:75px"onclick="getRes()"/></TD>
<TD><inputtype="button" value="/" style="width:75px"onclick="getNum('/')"/></TD>
</TR>
</TABLE>
</body>
</html>