Program.cs

public delegate void MathDelegate(int No1, int No2);

public class Rectangle
{

    public delegate void RectangleDelege(double Width, double Height);

    public void GetArea(double Width, double Height)
    {
        Console.WriteLine($"Area is {Width * Height}");
    }

    public void GetPerimeter(double Width, double Height) {
        Console.WriteLine($"Perimeter is {2 * (Width + Height)}");
    }

    // Declaring static Methods
    //Static Method
    public static void Add(int x, int y)
    {
        Console.WriteLine($"Addition of {x} and {y} is : {x + y}");
    }
    //Static Method
    public static void Sub(int x, int y)
    {
        Console.WriteLine($"Subtraction of {x} and {y} is : {x - y}");
    }
    //Non-Static Method
    public void Mul(int x, int y)
    {
        Console.WriteLine($"Multiplication of {x} and {y} is : {x * y}");
    }
    //Non-Static Method
    public void Div(int x, int y)
    {
        Console.WriteLine($"Division of {x} and {y} is : {x / y}");
    }


    static void Main(string[] args)
    {

        // First method to Multicast Delegate

        //Rectangle rect = new Rectangle();

        //RectangleDelege rectDelegate = new RectangleDelege(rect.GetArea);

        //rectDelegate += rect.GetPerimeter;

        //Delegate[] InvocationList = rectDelegate.GetInvocationList();

        //Console.WriteLine("InvocationList");

        //foreach(var item in InvocationList)
        //{
        //    Console.WriteLine($"    {item}");
        //}

        //Console.WriteLine();
        //Console.WriteLine("Invoking Multicast Delegate:");
        //rectDelegate(23.45, 67.89);
        //// rectDelegate.Invoke(13.45, 76.89);

        //Console.WriteLine();
        //Console.WriteLine("Invoking Multicast Delegate After Removing one Pipeline:");

        ////Removing a method from delegate object
        //rectDelegate -= rect.GetPerimeter;

        //rectDelegate.Invoke(13.45, 76.89);
        //Console.ReadKey();

        //Second Method to Multicast Delegates
        Rectangle rect2 = new Rectangle();

        MathDelegate del1 = new MathDelegate(Add);

        MathDelegate del2 = new MathDelegate(Rectangle.Sub);

        MathDelegate del3 = new MathDelegate(rect2.Mul);

        MathDelegate del4 = new MathDelegate(rect2.Div);

        // del5 will be the Multicast
        MathDelegate del5 = del1 + del2 + del3 + del4;

        Delegate[] invocationList = del5.GetInvocationList();

        Console.WriteLine("InvocationList:");

        foreach(var item in invocationList)
        {
            Console.WriteLine($" {item}");
        }

        Console.WriteLine();

        Console.WriteLine("Invoking Multicast Delegate::");
        del5.Invoke(20, 5);
        Console.WriteLine();

        Console.WriteLine("Invoking Multicast Delegate After Removing one Delegate:");
        del5 -= del2;
        del5(22, 7);

        Console.ReadKey();
    }
}