private double calculateResult(string sign) { double result = 0; if (sign.Equals("+")) { result = mathLib.AddDoubles(number1, number2); } if (sign.Equals("-")) { result = mathLib.SubDoubles(number1, number2); } if (sign.Equals("*")) { result = mathLib.MultDoubles(number1, number2); } if (sign.Equals("/")) { result = mathLib.DivDouble(number1, number2); } return(result); }