private void Button1_Click(object sender, EventArgs e)

        {

            int[] arr = { 500, 250, 125 };

            int n = arr.Length;

            MessageBox.Show(findGCD(arr, n).ToString());

        }

        static int gcd(int a, int b)

        {

            if (a == 0)

                return b;

            return gcd(b % a, a);

        }
        static int findGCD(int[] arr, int n)

        {

            int result = arr[0];

            for (int i = 1; i < n; i++)
            {
                result = gcd(arr[i], result);

                if (result == 1)
                {
                    return 1;
                }
            }

            return result;
        }