static void Main(string[] args)
        {
            PrimeNumber PNumber = new PrimeNumber();

            long sum   = 0;
            int  limit = 2000000;

            for (int i = 2; i <= limit; i++)
            {
                if (PNumber.isPrime(i))
                {
                    sum += i;
                }
            }
            Console.WriteLine("Sum of numbers below 2000000 is " + sum);
            Console.ReadLine();
        }