Java Program for fining factorial of a number

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Program for fining factorial of a number

In this article we will see different way to find out the factorial of a number .

Concept :

Factorial is mostly used in permutation and combination. It is calculated as the product of the all positive number from 1 to n. for example if the number is N , then the factorial would be ( 1 x 2 x 3 x ….. x N) .

The factorial value of 0 is ‘1’.
There is no factorial value for negative number .

Example : 

number =5 
factorial = 1 x 2 x 3 x 4 x 5 =120

Now we will see 2 different ways to do it.

By using for loop
By using while loop

Method 1: By using for loop

By using for loop we can calculate the factorial of a number.

Approach :

Enter a number .
Take a variable and initialize 1 into it .
Take a for loop form 1 to that number and for each step multiply the value with that variable .
Print the value .

Program :

import java.util.Scanner;
class Main{  
 public static void main(String args[])
 {  
    int x,f=1, n ;
    // creating object .
    Scanner sc = new Scanner(System.in);
    // entering a number .
    System.out.println("Enter a number :");
    n = sc.nextInt(); 
    sc.close();
  //calculating factorial value .    
  for(x=1;x<=n;x++)
  {    
      f=f*x;    
  }    
  // printing factorial value 
  System.out.println("Factorial of "+n+" = "+f);    
 }  
}

Output:

Enter a number :
5
Factorial of 5 = 120

Method 2: By using while loop

By using while loop we can calculate the factorial of a number.

Approach :

Enter a number .
Take a variable and initialize 1 into it .
Take a while loop form 1 to that number and for each step multiply the value with that variable .
Print the value .

Program:

import java.util.Scanner;
class Main
{  
 public static void main(String args[])
 {  
    int x=1,f=1, n ;
    // creating object .
    Scanner sc = new Scanner(System.in);
    // entering a number .
    System.out.println("Enter a number :");
    n = sc.nextInt();
    sc.close();
  //calculating factorial value .    
  while(x<=n)
        {
            f  = f * x;
            x++;
        }  
  // printing factorial value 
  System.out.println("Factorial of "+n+" = "+f);    
 }    
}

Output:

Enter a number :
5
Factorial of 5 = 120

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