public void RunEx04()
        {
            int myNum = 99;
            Factoral(myNum);
            Console.ReadLine();
        }

        static int Factoral(int num)
        {
            int factoral = num;

            if (num > 0)
            {
                factoral *= Factoral(num - 1);
                Console.WriteLine("Factoral of {0} is: {1}", num, factoral);
                return factoral;
            }
            else
            {
                return 1;
            }
        }