private void calculateCircleArea() { if (circleAreaCheckBox.Checked) { if (int.TryParse(circleRadiusTextBox.Text.Trim(), out radius)) { Figure2DService <Circle> circleService = new CircleService(); double circleArea = circleService.calculateArea(radius); String areaResult = String.Format("{0}. Circle area is: {1} for radius: {2}", counter++, circleArea, radius); Console.WriteLine(areaResult); result.Add(areaResult); } } }