Prototype round() Method

Syntax:

number.round();

Return Value:

Rounds the number to the nearest integer.

Example:

<html>
<head>
<title>Prototype examples</title>
<script type="text/javascript" 
   src="/javascript/prototype.js">
</script>
<script>

function showResult(){

   alert( "Math.round(4.5) : " + Math.round(4.5) );
   alert( "(4.5).round()  : " + (4.5).round() );
   alert( "(4.49).round()  : " + (4.49).round()  );
   alert( "(-4.5).round()  : " + (-4.5).round()  );
}

</script>
</head>

<body>

  <p>Click the button to see the result.</p>
  <br />
  <br />
  <input type="button" value="Result" onclick="showResult();"/>

</body>
</html>

To understand it in better way you can Try it yourself.