using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter a number");

        int number = Convert.ToInt32(Console.ReadLine());

        long fact = GetFactorial(number);

        Console.WriteLine("{0} factorial is {1}", number, fact);    

    }

    private static long GetFactorial(int number)

    {          

        if (number == 0)

        {

            return 1;

        }

        return number * GetFactorial(number-1);

    }

}

​

​

​