Factorial 

Uncommons Maths is a java library with nice math utilities and random number generators. This requires the library uncommons-maths-1.2.2.jar to be in classpath. The following example shows using Maths.factorial() API. It lets us to calculate the factorial in the range 0 - 20.

File Name  :   com/bethecoder/tutorials/uncommons/FactorialTest.java  Author  :   Sudhakar KV Email  :   [email protected]

package com.bethecoder.tutorials.uncommons; import org.uncommons.maths.Maths; public class FactorialTest {   /**    * @param args    */   public static void main(String[] args) {          int num = 5;     long factorial = Maths.factorial(num);     System.out.println("Factorial of " + num + " is " + factorial);          num = 10;     factorial = Maths.factorial(num);     System.out.println("Factorial of " + num + " is " + factorial);          num = 15;     factorial = Maths.factorial(num);     System.out.println("Factorial of " + num + " is " + factorial);   } }

Factorial of 5 is 120
Factorial of 10 is 3628800
Factorial of 15 is 1307674368000