C# Design a simple calculator using a switch case statement

Program: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace DecisionMaking3 { class Program { static void Main(string[] args) { Console.WriteLine("Calculator"); Console.WriteLine("----------------------------"); Console.WriteLine("1.Add"); Console.WriteLine("2.Substract"); Console.WriteLine("3.Multiply"); Console.WriteLine("4.Divide"); Console.Write("Enter Choice(1-4):"); int ch = Int32.Parse(Console.ReadLine()); int a, b, c; switch(ch) { case 1: Console.Write("Enter A:"); a = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter B:"); b = Convert.ToInt32(Console.ReadLine()); c = a + b; Console.WriteLine("Sum = {0}", c); break; case 2: Console.Write("Enter A:"); a = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter B:"); b = Convert.ToInt32(Console.ReadLine()); c = a - b; Console.WriteLine("Difference = {0}", c); break; case 3: Console.Write("Enter A:"); a = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter B:"); b = Convert.ToInt32(Console.ReadLine()); c = a * b; Console.WriteLine("Product = {0}", c); break; case 4: Console.Write("Enter A:"); a = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter B:"); b = Convert.ToInt32(Console.ReadLine()); c = a / b; Console.WriteLine("Quotient = {0}", c); break; default: Console.WriteLine("Invalid Choice"); break; } Console.ReadKey(); } } } Output First run: Calculator ---------------------------- 1.Add 2.Substract 3.Multiply 4.Divide Enter Choice(1-4):1 Enter A:10 Enter B:20 Sum = 30 Second run: Calculator ---------------------------- 1.Add 2.Substract 3.Multiply 4.Divide Enter Choice(1-4):4 Enter A:10 Enter B:20 Quotient = 0 Third run: Calculator ---------------------------- 1.Add 2.Substract 3.Multiply 4.Divide Enter Choice(1-4):5 Invalid Choice