Multicast Delegates in C#

using System;

namespace NilPointer
{
    class Program
    {
        public delegate double CalCulate(double a, double b);

        public static double Add(double a, double b)
        {
            return a + b;
        }

        public static double Sub(double a, double b)
        {
            return a - b;
        }

        public static double Mul(double a, double b)
        {
            return a * b;
        }

        static void Main(string[] args)
        {
            CalCulate calCulate = Add;
            calCulate += Sub;
            calCulate += Mul;

            var result1 = calCulate(10, 2);
            Console.WriteLine("result 1: " + result1);

            calCulate -= Sub;
            calCulate -= Mul;
            var result2 = calCulate(10, 2);
            Console.WriteLine("result 2: " + result2);

            Console.ReadLine();
        }
    }
}

Output

result 1: 20
result 2: 12