Java Program to Find Factorial of a Number

Factorial of a number is the multiplication of a number with all the integers less than it. Factorial of a number is written as the number followed by exclamation symbol !. For Example, Factorial of 4 is written as 4!.

n! = n * (n - 1)!
0! = 1
1! = 1
4! = 4 * 3 * 2 * 1 = 24
5! = 5 * 4 * 3 * 2 * 1 = 120
6! = 6 * 5 * 4 * 3 * 2 * 1 = 720

Algorithm

1. Set factorial as 1
2. Store the Number for which you want to find the factorial in a variable say i
3. Multiply factorial * i and store in factorial
4. Decrement i and store in i itself
5. Repeat the above steps until i=1

Factorial of a Number - Java Program

public class FactorialOfANumber {
	public static void main (String args[]) {

		int num = 5;
		System.out.print("Factorial of the Number " + num + " = ");
		int factorial=1;

		for(int i = num; i >= 1 ; i--) {
			System.out.print(""+ i );

			factorial = factorial * i;

			if(i!=1) System.out.print(" * ");
		}
		System.out.print("=" + factorial);
	}
}

Output of the Java program would be:

Factorial of the Number 5 = 5 * 4 * 3 * 2 * 1=120

Factorial of Some Numbers