Лучше вообще вот так
<!DOCTYPE html>
<html>
<head>
<meta http-equiv='Content-Type' content='text/html; charset=windows-1251' />
<script src='https://code.jquery.com/jquery-latest.js'></script>
<!--
<script src="https://code.angularjs.org/1.3.9/angular.min.js"></script>
<script src="https://code.angularjs.org/1.3.9/angular-route.js"></script>
-->
<style type='text/css'>
</style>
<script type='text/javascript'>
$(function(){
var num = $("#num");
var time = $("#time");
var res = $("#res span");
var sub = $("#sub");
var numres;
var result;
$('#cal-form').submit(function(){
numres = 250 * num.val();
res.text(numres);
return false;
});
});
</script>
</head>
<body>
<form id="cal-form">
<div>
<input id="num" type="text" value="" />
</div>
<div>
<input id="time" type="text" value="" />
</div>
<div>
<input id="sub" type="submit" value="Рассчитать" />
</div>
</form>
<div>
<p id="res">Итог: <span>0</span> руб.</p>
</div>
</body>
</html>