<SCRIPT LANGUAGE="JavaScript">
<!--
var Number1 = "";
var Number2 = "";
var NewNumber = "blank";
var opvalue = "";

function Display(displaynumber) {
document.calculator.answer.value = displaynumber;
}

function ClearCalc() {              // 清空
Number1 = "";
Number2 = "";
NewNumber = "blank";
Display("");
}


function CheckNumber(answer) {         // 显示数字
if(answer == ".") {
Number = document.calculator.answer.value;
if(Number.indexOf(".") != -1) {
answer = "";
   }
}
if(NewNumber == "yes") {
Number2 += answer;
Display(Number2);
}
else {
if(NewNumber == "blank") {
Number1 = answer;
Number2 = "";
NewNumber = "no";
}
else {
Number1 += answer;
}
Display(Number1);
   }
}

function AddButton(x) {                // 加法函数
if(x == 1) EqualButton();
if(Number2 != "") {
Number1 = parseFloat(Number1) + parseFloat(Number2);
}
NewNumber = "yes";
opvalue = '+';
Display(Number1);
}

function SubButton(x) {                // 减法函数
if(x == 1) EqualButton();
if(Number2 != "") {
Number1 = parseFloat(Number1) - parseFloat(Number2);
}
NewNumber = "yes";
opvalue = '-';
Display(Number1);
}

function MultButton(x) {               // 乘法
if(x == 1) EqualButton();
if(Number2 != "") {
Number1 = parseFloat(Number1) * parseFloat(Number2);
}
NewNumber = "yes";
opvalue = '*';
Display(Number1);
}
function DivButton(x) {                // 除法
if(x == 1) EqualButton();
if(Number2 != "") {
Number1 = parseFloat(Number1) / parseFloat(Number2);
}
NewNumber = "yes";
opvalue = '/';
Display(Number1);
}

function SqrtButton() {                // 平方按钮
Number1 = Math.sqrt(Number1);
NewNumber = "blank";
Display(Number1);
}

function RecipButton() {                // 分数
Number1 = 1/Number1;
NewNumber = "blank";
Display(Number1);
}
function NegateButton() {                // 正负值
Number1 = parseFloat(-Number1);
NewNumber = "no";
Display(Number1);
}
function EqualButton() {
if(opvalue == '+') AddButton(0);          // 加法
if(opvalue == '-') SubButton(0);          // 减法
if(opvalue == '*') MultButton(0);         // 乘法
if(opvalue == '/') DivButton(0);          // 除法
Number2 = "";
opvalue = "";
}
// -->
</script>
<form name="calculator">
<table bgcolor="#777777" width=220>
<tr><td>
<table bgcolor="#aaaaaa" border=1>
<tr><td>
<table border=0 cellpadding=0>
<tr>
                    <td bgcolor="#000000" align=center><font color="#ffffff"><b>计&nbsp;算&nbsp;器</b></font></div>
                    </td>
                  </tr>
<tr><td>
<table width="100%" border=0>
<tr><td colspan=6><input type="text" name="answer" size=37 maxlength=37 onChange="CheckNumber(this.value)"></td></tr>
<tr>
<td><input type="button" name="calc7" value="  7  " onClick="CheckNumber('7'); return false;"></td>
<td><input type="button" name="calc8" value="  8  " onClick="CheckNumber('8'); return false;"></td>
<td><input type="button" name="calc9" value="  9  " onClick="CheckNumber('9'); return false;"></td>
<td><input type="button" name="divide"  value="  /  " onClick="DivButton(1); return false;"></td>
<td><input type="reset" name="C" value="  C  " onClick="ClearCalc(); return false;"></td></tr>
<tr>
<td><input type="button" name="calc4" value="  4  " onClick="CheckNumber('4'); return false;"></td>
<td><input type="button" name="calc5" value="  5  " onClick="CheckNumber('5'); return false;"></td>
<td><input type="button" name="calc6" value="  6  " onClick="CheckNumber('6'); return false;"></td>
<td><input type="button" name="multiply"  value="  *  " onClick="MultButton(1); return false;"></td>
<td><input type="button" name="sqrt" value=" sqrt" onClick="SqrtButton(); return false;"></td></tr>
<tr>
<td><input type="button" name="calc1" value="  1  " onClick="CheckNumber('1'); return false;"></td>
<td><input type="button" name="calc2" value="  2  " onClick="CheckNumber('2'); return false;"></td>
<td><input type="button" name="calc3" value="  3  " onClick="CheckNumber('3'); return false;"></td>
<td><input type="button" name="minus"  value="  -  " onClick="SubButton(1); return false;"></td>
<td><input type="button" name="recip" value=" 1/x " onClick="RecipButton(); return false;"></td></tr>
<tr>
<td><input type="button" name="calc0" value="  0  " onClick="CheckNumber('0'); return false;"></td>
<td><input type="button" name="negate" value=" +/- " onClick="NegateButton(); return false;"></td>
<td><input type="button" name="dot" value="  .  " onClick="CheckNumber('.'); return false;"></td>
<td><input type="button" name="plus"  value="  +  " onClick="AddButton(1); return false;"></td>
<td><input type="button" name="equal"  value="  =  " onClick="EqualButton(); return false;"></td>
</tr>
</table>
</td></tr>
</table>
</td></tr>
</table>
</td></tr>
</table>
</form>