using System;

namespace AbstractClassExample

{

    //Creating an Abstract Class

    public abstract class BaseClass

    {

        //Non abstract method

        public int addition(int a, int b)

        {

          return a + b;

        }

​

        //An abstract method, overridden in derived class

        public abstract int multiplication(int a, int b);

    }

​

    //child class, derived from BaseClass

    public class DerivedClass:BaseClass

    {

        public static void Main(string[] args)

        {

           DerivedClass cal = new DerivedClass();

           int added = cal.addition(10,20);

           int multiplied = cal.multiplication(10,2);

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

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

        }

        public override int multiplication(int a, int b)

        {

           return a * b;

        }

    }

}