Finding Factorial of a Number in Java

• One of the famous java interview program for freshers is finding factorial of a number using java program
• Calculating the factorial of a number using java example program with recursion.


• Factorial number means multiplication of all positive integer from one to that number.
• n!=1*2*3.......*(n-1)*n.
• Here ! represents factorial.
• Two factorial:   2!=  2*1=2
• Three factorial: 3!= 3*2*1=6.
• Four factorial :  4!= 4*3*2*1=24.
• Five factorial:    5!= 5*4*3*2*1=120.
• Six factorial:      6!= 6*5*4*3*2*1=720
• Seven factorial: 7!= 7*6*5*4*3*2*1=5040
• Eight factorial:   8!= 8* 7*6*5*4*3*2*1=40320.

• By using loops we can find factorial of given number.
• Lets how can we find factorial of a number using java program without recursion.

Program #1: Java program to find factorial of a number using for loop

1. package interviewprograms.instanceofjava;
2. 
   
3. import java.util.Scanner;
4. 
   
5. public class FactiorialProgram {
6. 
   
7. public static void main(String args[]){
9. Scanner in = new Scanner(System.in);
10. System.out.println("Enter a number to find factorial");
12. int n= in.nextInt();
13. int fact=1;
14. 
    
15. for (int i = 1; i < n; i++) {
16. fact=fact*i;
18. }
19. 
    
20. System.out.println("Factorial of "+n+" is "+fact);
21. 
    
22. }
23. }

Output:

2. Enter a number to find factorial
3. 5
4. Factorial of 5 is 120

Program #2: Java program to find factorial of a number using recursion.

1. package interviewprograms.instanceofjava;
2. 
   
3. import java.util.Scanner;
4. 
   
5. public class FactiorialProgram {
6. 
   
7. public static void main(String args[]){
9. Scanner in = new Scanner(System.in);
10. System.out.println("Enter a number to find factorial");
12. int n= in.nextInt();
13. int fact=1;
14. 
    
15. for (int i = 1; i < n; i++) {
16. fact=fact*i;
18. }
19. 
    
20. System.out.println("Factorial of "+n+" is "+fact);
21. 
    
22. }
23. }

Output:

1. 
   
2. Enter a number to find factorial
3. 5
4. Factorial of 5 is 120

Program #3: Java program to find factorial of a number using recursion (Eclipse)