using System;

namespace Singleton

{

 public class Program

 {

 public static void Main(string[] args)

 {

 Calculate.Instance.ValueOne = 10.5;

 Calculate.Instance.ValueTwo = 5.5;

 Console.WriteLine("Addition : " + Calculate.Instance.Addition());

 Console.WriteLine("Subtraction : " + Calculate.Instance.Subtraction());

 Console.WriteLine("Multiplication : " + Calculate.Instance.Multiplication());

 Console.WriteLine("Division : " + Calculate.Instance.Division());

 Console.WriteLine("\n----------------------\n");

 Calculate.Instance.ValueTwo = 10.5;

 Console.WriteLine("Addition : " + Calculate.Instance.Addition());

 Console.WriteLine("Subtraction : " + Calculate.Instance.Subtraction());

 Console.WriteLine("Multiplication : " + Calculate.Instance.Multiplication());

 Console.WriteLine("Division : " + Calculate.Instance.Division());

 Console.ReadLine();

 }

 }

// Note: Once a class is defined as a sealed class, this class cannot be inherited.

 public sealed class Calculate

 {

 private Calculate()

 {

 }

 private static Calculate instance = null;

 public static Calculate Instance

 {

 get

 {

 if (instance == null)

 {

 instance = new Calculate();

 }

 return instance;

 }

 }

 public double ValueOne { get; set; }

 public double ValueTwo { get; set; }

 public double Addition()

 {

 return ValueOne + ValueTwo; 

​

 }

 public double Subtraction()

 {

 return ValueOne - ValueTwo;

 }

 public double Multiplication()

 {

 return ValueOne * ValueTwo;

 }

 public double Division()

 {

 return ValueOne / ValueTwo;

 }

 }

}