using System;

public class Program

{

    public static void Main()

    {

        var calc =new Calculate();

        int a = 5;

        int b =6;

        Console.WriteLine("sum");

        Console.WriteLine(calc.DoSum(a,b).ToString());

        Console.WriteLine("subtraction");

        Console.WriteLine(calc.DoSubtract(a,b).ToString());

        Console.WriteLine("multiplication");

        Console.WriteLine(calc.Multiplication(a,b).ToString());

    }

}

public class Calculate

{

    internal int DoSum(int a , int b)

    {

        return a+b;

    }

    internal int DoSubtract(int a, int b)

    {

        return a-b;

    }

    internal int Multiplication(int a, int b)

    {

        return a*b;

    }

}

​

​

​