Самое часто встречаемое число.

{
            Random rand = new Random();

            do
            {
                int[] random_num = new int[50];
                int[] average = new int[50];
                int[] score = new int[50];
                int win = 0, max = 0;
                for (int i = 0, x = 1; i != random_num.Length; i++, x++)
                {
                    random_num[i] = rand.Next(1, 51);
                    average[i] = x;
                    score[i] = 0;
                }
                for (int i = 0; i != random_num.Length; i++)
                {
                    for (int j = 0; j != random_num.Length; j++)
                    {
                        if (random_num[i] == average[j])
                            score[j]++;
                    }
                }
                for (int i = 0; i != random_num.Length; i++)
                {
                    if (score[i] > max)
                    {
                        win = i++;
                        max = win;
                    }
                }
                for (int i = 0, x = 1; i != random_num.Length; i++, x++)
                {
                    Console.Write(random_num[i] + "; ");
                }
                Console.WriteLine();
                for (int i = 0, x = 1; i != random_num.Length; i++, x++)
                {
                    Console.Write(x + " - " + score[i]);
                    Console.WriteLine();
                }
                Console.WriteLine();
                Console.WriteLine(win+1);
                Console.ReadKey();
                Console.Clear();
            } while (true);
        }