// Java Document
<!-- Paste this code into an external JavaScript file named: calc.js  -->

/* This script and many more are available free online at
The JavaScript Source :: http://javascript.internet.com
Created by: Lee Underwood :: http://javascript.internet.com/ */

function circum() {
  var radius = prompt("Enter the radius of the circle","");
  var circle = 2 * Math.PI * radius;
  alert("The circumference is "+circle+".")
}