public static void Main() { CMyMathClass objCMyMathClass = new CMyMathClass(); //IMyMath objIMyMath = (IMyMath) objCMyMathClass; int num1 = 75, num2 = 25, res = 0; res = objCMyMathClass.SumOfTwoIntegers(num1, num2); Console.WriteLine("The Sum Of " + num1 + " and " + num2 + " is " + res); res = objCMyMathClass.SubtractionOfTwoIntegers(num1, num2); Console.WriteLine("The Subtraction Of " + num1 + " and " + num2 + " is " + res); }