Java program to find factorial of a number

In this post, you will learn how to find the factorial of a number using the Java programming language.

The factorial is normally used in different areas of mathematics, including algebra, mathematical analysis, and combinations and permutations. The factorial of a number n is denoted by n!. This is the product of all positive numbers less than or equal to n. It is calculated as-

n! = n X (n-1) X (n-3) X ……… X 3 X 2 X 1

Example of factorial

Suppose we want to get a factorial of 7, then the factorial will be-

7! = 7 X 6 X 5 X 4 X 3 X 2 X 1
5040

There are different ways to write a Java programme to find the factorial of a number. Here we have mentioned three ways:

Find factorial of a number using for loop in Java

In the given program, we have used the for loop to iterate through all numbers between 1 and the given number 7, and get the product of each number.

public class FindFactorial{  
 public static void main(String args[]){  
  int x,fact=1;  
  int num=7;
  
  for(x=1;x<=num;x++){    
      fact=fact*x;    
  }    
  System.out.println("Factorial of "+num+" is: "+fact);    
 }  
}  

Factorial of 7 is: 5040

Find factorial of a number using while loop in Java

In the given program, we have used the while loop to iterate through all numbers between 1 and the given number 6, and get the product of each number.

public class FindFactorial{  
 public static void main(String args[]){  
    int num = 6, i = 1;
    long fact = 1;
    while(i <= num)
    {
        fact *= i;
        i++;
    }
    System.out.printf("Factorial of %d = %d", num, fact);   
 }  
}  

Factorial of 6 = 720

Find factorial of a number using do while loop in Java

In the given Java program, we have used the do while loop to find the factorial of a number.

import java.util.Scanner;

public class FindFactorial
{
	public static void main(String arg[])
	{
        long num,fact=1;
	
	    Scanner sc=new Scanner(System.in);
	    System.out.println("Enter number: ");
            num=sc.nextLong();
                
            int i=1;
            do
            {
                fact=fact*i;
                i++;
            }
 	        while(i<=num);
        System.out.println("Factorial of "+num+" is: "+fact);
	}
}

Enter number: 7
Factorial of 7 is: 5040

Find factorial of a number using recursion in Java

Here is the Java program to find the factorial of a number using the recursion function. A recursion function is a function that is called by itself. If the number is equal to 0, it returns 1. The factorial of a number less than equal to 0 does not exist. If the number is greater than 1, the function calls recursively and finds the factorial of a number.

public class FindFactorial{  
 static int factorial(int num){    
  if(num == 0)    
    return 1;    
  else    
    return(num * factorial(num-1));    
 }    
 
 public static void main(String args[]){  
  int i,fact=1;  
  int number=4;  
  fact = factorial(number);   
  System.out.println("Factorial of "+number+" is: "+fact);    
 }  
}  

Factorial of 6 = 720

Find factorial of a number using single line solution in Java

Here, we have mentioned the simplest solution to find the factorial of a number in Java.

public class FindFactorial{  
    static int factorial(int n)
    {
        return (n == 1 || n == 0) ? 1 : n * factorial(n - 1);
    }   
 
    public static void main(String args[]){  
        int fact = 1;  
        int num = 8;  
        fact = factorial(num);   
        System.out.println("Factorial of "+num+" is: "+fact);    
    }  
}  

Factorial of 8 is: 40320

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