public void CanSubtractMultipleDigits() { Assert.That(_controller.CanEnterMultipleDigits(13), Is.EqualTo(2)); //i want to show that if you enter multiple digits then subtract (which will be in the code) 11, the answer will be 2. Assert.That(_controller.CanEnterMultipleDigits(97), Is.EqualTo(10)); //same story, i want to show that multiple digits '97' minus a multiple digit '87', will result in '10'. }