static void Main(string[] args) { Console.WriteLine("first digit: "); double a = Convert.ToDouble(Console.ReadLine()); Console.WriteLine("second digit: "); double b = Convert.ToDouble(Console.ReadLine()); Console.WriteLine("Operators: 1-'+', 2-'-', 3-'*', 4-'/', 5-'^'"); int _operator = Convert.ToInt32(Console.ReadLine()); if (_operator > 0 && _operator < 6) { switch (_operator) { case 1: Summ summ = new Summ(); summ.Result(a, b); break; case 2: Subtraction subtraction = new Subtraction(); subtraction.Result(a, b); break; case 3: Multiply multiply = new Multiply(); multiply.Result(a, b); break; case 4: Dividing dividing = new Dividing(); dividing.Result(a, b); break; case 5: Degree degree = new Degree(); degree.Result(a, b); break; } } else { Console.WriteLine("Operator not found"); } Console.ReadKey(); }