MY CODE >> Factorial Calculator
/* Tommy Martin
 * 11/15/2012
 * 
 * This Program Calculates Factorials by using a Recursive Algorithm
 * 
 * Program.cs
 */

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            double num = 0;
            Console.WriteLine("Factorials");
            Console.Write("Please enter an integer: ");
            try
            {
                num = Convert.ToDouble(Console.ReadLine());
                
                Factorial call = new Factorial();
                Console.WriteLine("\n{0}! is: {1}", num, call.FactCalc(num));
            }
            catch (Exception e) 
            {
                Console.WriteLine("{0} Exception caught.", e);
                Console.WriteLine("Only integers can be used...");
            }

            Console.Write("\nPress any key to continue...");
            Console.ReadLine();
        }
    }
}
/* Tommy Martin
 * 11/15/2012
 * 
 * The pseudocode for this algorithm was copied from
 * Richard Johnsonbaugh's
 * Discrete Mathematics, Seventh Edition, page 214 Algorithm 4.4.2
 * 2009 by Pearson Education, Inc: Upper Saddle River, NJ
 * 
 * Factorial.cs
 */

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

namespace ConsoleApplication1
{
    class Factorial
    {
        public double FactCalc(double n)
        {
            if (n == 0)
                return 1;
            return n * FactCalc(n - 1);
        }
    }
}