int[] Num = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
int Sum = Num.Sum();

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

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {   
//create array num with the initializing value
            int[] Num = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            Console.WriteLine("Calculating the sum of all the elements of the array :");
//Num.Sum() is used to add the value of the Num array
            int Sum = Num.Sum();
            Console.WriteLine("The Sum is {0}", Sum);
            Console.ReadLine();
        }
    }
}