PatternSingleton

using System;

namespace Singletone
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(Singleton.GetInstance().SecretPassword);
            Console.WriteLine(Singleton.GetInstance().SecretPassword);
            Console.ReadKey();
        }
    }

    public class Singleton
    {
        private static Singleton Instance = new Singleton();
        private Random _random = new Random();
        public int SecretPassword { get; private set; }

        private Singleton()
        {
            SecretPassword = _random.Next(10000, 100000);
        }

        public static Singleton GetInstance()
        {
            return Instance;
        }
    }
}