[html]<html>
<head>
<meta charset="utf-8">
<link rel="stylesheet" type="text/css" href="style.css" />
<title>HTML калькулятор</title>
</head>
<body>
<form name="calc" class="wrapper">
<table class="main">
<tr class="display">
<td colspan="4"><input type="text" name="input"></td>
</tr>
<tr class="buttons">
<td><input type="button" value="1" OnClick="calc.input.value += '1'"></td>
<td><input type="button" value="2" OnClick="calc.input.value += '2'"></td>
<td><input type="button" value="3" OnClick="calc.input.value += '3'"></td>
<td><input type="button" value="+" OnClick="calc.input.value += '+'"></td>
</tr>
<tr class="buttons">
<td><input type="button" value="4" OnClick="calc.input.value += '4'"></td>
<td><input type="button" value="5" OnClick="calc.input.value += '5'"></td>
<td><input type="button" value="6" OnClick="calc.input.value += '6'"></td>
<td><input type="button" value="-" OnClick="calc.input.value += '-'"></td>
</tr>
<tr class="buttons">
<td><input type="button" value="7" OnClick="calc.input.value += '7'"></td>
<td><input type="button" value="8" OnClick="calc.input.value += '8'"></td>
<td><input type="button" value="9" OnClick="calc.input.value += '9'"></td>
<td><input type="button" value="x" OnClick="calc.input.value += '*'"></td>
</tr>
<tr class="buttons">
<td><input type="reset" value="c" OnClick="calc.input.value = ''"></td>
<td><input type="button" value="0" OnClick="calc.input.value += '0'"></td>
<td><input type="button" value="=" OnClick="calc.input.value = eval(calc.input.value)"></td>
<td><input type="button" value="/" OnClick="calc.input.value += '/'"></td>
</tr>
<table>
</form>
</body>
</html>[/html]
Онлайн калькулятор:)