//Button << private void BtnPrevious_Click(object sender, RoutedEventArgs e) { double PreviousResult = Calculations.GiveBackPreviousElementOfResultMemory(); double ExceptionValue = -9999.6677712; if (PreviousResult != ExceptionValue && PreviousResult != 0) { TbResultMemory.Text = PreviousResult.ToString(); Calculations.DecrementResultMemoryNavigatorByOne(); } }