Factorial program in C# – Simple ways to find factorial of a number

Factorial program in C# with example and logic. l

For Example to find the factorial of a number 6 is 720.
(6!=6*5*4*3*2*1=720)

How to find factorial?

The factorial of a number denoted as n!.

Factorial Formula.

n!=n*(n-1)*(n-2)*…*1

For suppose to find the factorial of a number 6 as based on above formula.
6!=6*(6-1)*(6-2)*(6-3)*(6-4)*(6-5)
=6*5*4*3*2*1
=720

Notes:

  • The factorial number is product of number in its descending order.
  • Factorial of 0 is 0!=1
  • No factorial for Negative Number.

Example of factorial program in C# using for loop

using System;
/* 
C# example for finding factorial of a number using for loop
*/

class Program
    {
        static void Main(string[] args)
        {
            //initialized number by 6
            int number = 6; 

            //initialized factorial by 1
            int factorial=1;
            for (int j = number; j >= 1; j--)
            {
                factorial = factorial * j;

            }
            Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
        }
    }
}

Output

the factorial of the number 6 = 720

Example of factorial program in C# using while loop

/*  
  C# example for finding factorial of a number using while loop
 */
 
    class Program
    {
        static void Main(string[] args)
        {
            //initialized number by 6
            int number = 6; 

            //initialized factorial by 1
            int factorial=1;
            
            int j = number;

            while (j >= 1)
            {
                factorial = factorial * j;
                j = j - 1;
            }
            Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
        }
    }

Example of factorial program in C# using do-while loop

  class Program
    {
     
        static void Main(string[] args)
        {
            //initialized number by 6
            int number = 6; 

            //initialized factorial by 1
            int factorial=1;
            
            int j = number;

            do
            {
                factorial = factorial * j;
                j = j - 1;

            } while (j >= 1);
          
            Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
        }
 }

Example of factorial program in C# using function

 
 class Program
    {
     
        static void Main(string[] args)
        {
            //initialized number by 6
            int number = 6; 

            //initialized factorial by 1
            int factorial=1;
            
            Program p = new Program();
            //call the function by passing value to find the factorial
            factorial = p.fact(number);

            Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
        }

        public int  fact(int number)
        {
            int factorial = 1;
            int j = number;
            while (j >= 1)
            {
                factorial = factorial * j;
                j = j - 1;
            }
            return factorial;
        }
    }

Example of factorial program in C# using Recursive function

 
 class Program
    {
     
        static void Main(string[] args)
        {
            //initialized number by 6
            int number = 6; 

            //initialized factorial by 1
            int factorial=1;
            

            Program p = new Program();
            factorial = p.fact(number);

            Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
        }

       
        public int fact(int number)
        {
            
            if (number==0 || number==1)
            {
                return 1;
            }
            else
            {
                return number * fact(number - 1);
            }                     
           
        }

    }
Factorial program in C# – Simple ways to find factorial of a number

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