Console Application ArrayGrades C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Average {
    class Program {
        static void Main(string[] args) {
            double grade1,grade2,grade3,grade4,grade5,grade6,grade7,grade8,grade9,grade10,avg;
            double[] grade = new double[10];

            Console.WriteLine("Please enter a grade: ");
            grade[1] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[2] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[3] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[4] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[5] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[6] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[7] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[8] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[9] = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a grade: ");
            grade[10] = double.Parse(Console.ReadLine());
            avg = grade[1] + grade[2] + grade[3] + grade[4] + grade[5] + grade[6] + grade[7] + grade[8] + grade[9] + grade[10] / 10;
            Console.WriteLine("The Average is: " + avg );
            Console.WriteLine(avg);
            Console.ReadLine();
        }
    }
}