Finding Factorial of a Number in C# using Abstract Class

In this code snippet enter any number and you can find the factorial of that number up to 40.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication30
{
    class Program
    {
        static void Main(string[] args)
        {
            Class2 class22 = new Class2();
            class22.factorial();
            Console.ReadKey();
        }
    }
}

This is a program through which you can find the factorial of a number....

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication30
{
    public abstract class Class1
    {
        public abstract void factorial();
    }
    public class Class2 : Class1
    {
        public override void factorial()
        {
            Console.WriteLine("enter a number to find the factorial: ");
            int n = Convert.ToInt32(Console.ReadLine());
            long fact = 1;
            for (int i = 1; i <= n; i++)
            {
                fact = fact * i;
            }
            Console.WriteLine("The factorial: {0}", fact);

        }
    }
}