NWW i NWD w C#

        static void Main(string[] args)
        {
            start:
            Console.WriteLine("Chcesz obliczyc NWD(1) czy NWW(2)?: ");
            int a = int.Parse(Console.ReadLine());
            switch (a)
            {
                case 1:
                    NWD();
                    break;
                case 2:
                    NWW();
                    break;
                default:
                    Console.Clear();
                    Console.WriteLine("Blad, wybierz 1 lub 2.");
                    goto start;
                    break;
            }
            Console.ReadKey();
        }
           private new static void NWD()
           {
               Console.Clear();
               Console.WriteLine("Podaj dwie liczby calkowite, aby obliczyc NWD: ");
               double a = double.Parse(Console.ReadLine());
               double b = double.Parse(Console.ReadLine());
               double w;
               while (b != 0)
               {
                   w = a % b;
                   a = b;
                   b = w;
               }
               Console.WriteLine("NWD wynosi: {0}",a);
           }
           private new static void NWW()
           {
               Console.Clear();
               Console.WriteLine("Podaj dwie liczby calkowite, aby obliczyc NWW: ");
               double a = double.Parse(Console.ReadLine());
               double b = double.Parse(Console.ReadLine());
               double x = a * b;
               double w;
               while (b != 0)
               {
                   w = a % b;
                   a = b;
                   b = w;
               }
               double nww = x / a;
               Console.WriteLine("NWW wynosi: {0}", nww);
           }