Average function Error

Hello,
I'm trying to make the following function:
- it takes a number n (Console.ReadLine) which defines the amount of numbers we want to add.
- it asks n times the number we want to add to the list
- it gives the average of the entered numbers.

        static int Fonc_question(int n) // This function asks the questions
        {
            int[] questions = new int[n];
            int q = n;
            int r = n;
            int i=0;
            int res =0;
            while (n > 0)
            {
                q -= 1;
                Console.WriteLine("Nombre "+ (n) + ":");
                 questions[(n-(q-1))] = Convert.ToInt32(Console.ReadLine());
                n=n-1;
            }
            if (n <= 0)
            {
                while (r > 0) // I'm having troubles here in order to get all the numbers I've entered so that i may do a sum of them and then divide them.
                {
                    res +=r;
                    r = r - 1;
                    
                }
                Console.Writeline(res/n);
            }
            Console.ReadLine();
            return n;
        }
        static void Main(string[] args)
        {
            int nombre;
            Console.WriteLine("Combien de nombres ?"); // How many numbers ?
            nombre = Convert.ToInt32(Console.ReadLine());
            Fonc_question(nombre);
        }

Any ideas ?