private void EqualsBtn_Click(object sender, RoutedEventArgs e) { if (double.TryParse(resultLabel.Content.ToString(), out double newNumber)) { switch (SelectedOperator) { case SelectedOperator.Sum: result = SimpleMath.Sum(lastNumber, newNumber); break; case SelectedOperator.Subtract: result = SimpleMath.Substract(lastNumber, newNumber); break; case SelectedOperator.Multiply: result = SimpleMath.Multiply(lastNumber, newNumber); break; case SelectedOperator.Divide: result = SimpleMath.Divide(lastNumber, newNumber); break; } resultLabel.Content = result; } }