using System;

​

namespace ExtensionMethod

{

    public class Program

    {

        public static void Main(string[] args)

        {

            Console.WriteLine("Enter a string:");

            string str = Console.ReadLine();

            Console.WriteLine("Random Number Appended to String:\n" + RandomNumberGenerator.AppendRandomNumberToString(new Random(), str));

        }

    }

​

    public static class RandomNumberGenerator

    {

        public static string AppendRandomNumberToString(this Random number, string str)

        {

            return str + number.Next();

        }

    }

}

​