How can i sum two or more numbers(possibility for client to enter two or more numbers) same for Subtraction, Multiplication and Division c# : using System;
using System.Linq;

namespace Kalkulator
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            switch (ChooseOperation())
            {
                case "1":
                    Addition();
                    break;

                case "2":
                    Subtraction();
                    break;

                case "3":
                    Multiplication();
                    break;

                case "4":
                    Division();
                    break;

                default:
                    break;
            }
        }//I'm trying to make 

        private static string ChooseOperation()
        {
            string choose = "Choose from 1 to 4 for operation: \n 1.Addition\n 2.Subtraction\n 3.Multiplication\n 4.Division";

            string[] option = { "1", "2", "3", "4" };
            Console.WriteLine(choose);
            string operation = Console.ReadLine();

            while (!option.Contains(operation))
            {
                Console.WriteLine("You have to enter right option!");
                Console.WriteLine(choose);
                operation = Console.ReadLine();
            }
            return operation;
        }

        private static int[] ChooseOperands()
        {
            int[] operands = new int[2]; 
            Console.Write("Enter first operand: ");
            operands[0] = int.Parse(Console.ReadLine());
            Console.Write("Enter second operand: ");
            operands[1] = int.Parse(Console.ReadLine());
            return operands;
        }

        private static void Addition()
        {
            Console.WriteLine("You selected Addition (+)");

            int[] operands = ChooseOperands();
            int result = 0;

           
           
                for (int index = 1; index < operands.Length; index++)
                    result += operands[index];
           

            Console.WriteLine();
            Console.WriteLine("Addition result: {0}", result);
            Console.ReadKey();
        }

        private static void Subtraction()
        {
            Console.WriteLine("You selected Subtraction (-)");

            int[] operands = ChooseOperands();
            int result = operands[0];
           
           
                for (int index = 1; index < operands.Length; index++)
                    result -= operands[index];
           

            Console.WriteLine();
            Console.WriteLine("Subtraction result: {0}", result);
            Console.ReadKey();
        }

        private static void Multiplication()
        {
            Console.WriteLine("You selected Multiplication (*)");

            int[] operands = ChooseOperands();
            int result = operands[0];

            for (int index = 1; index < operands.Length; index++)
                result *= operands[index];

            Console.WriteLine();
            Console.WriteLine("Multiplication result: {0}", result);
            Console.ReadKey();
        }

        private static void Division()
        {
            Console.WriteLine("You selected Division (/)");

            int[] operands = ChooseOperands();
            int result = operands[0];

            for (int index = 1; index < operands.Length; index++)
                result /= operands[index];

            Console.WriteLine();
            Console.WriteLine("Division result: {0}", result);
            Console.ReadKey();
        }
    }
}//i' m working on simplified calculator where user have to put 2 or more numbers for four operations: 1.Addition 2.Subtraction 3.Multiplication 4.Division 
,but every time when I put more then two numbers its not working?//