protected void Page_Load( object sender, EventArgs e )
        {

        }

        protected void groundRadioButton_CheckedChanged( object sender, EventArgs e )
        {
            performCalculation();
        }

        protected void airMailRadioButton_CheckedChanged( object sender, EventArgs e )
        {
            performCalculation();
        }

        protected void nextDayRadioButton_CheckedChanged( object sender, EventArgs e )
        {
            performCalculation();
        }



        private void performCalculation()
        {
           //Are there values put in the textboxes?
            if (widthTextBox.Text.Trim().Length == 0 && heightTextBox.Text.Trim().Length == 0) return;

           //Is a shipping method selected?
            if (!groundRadioButton.Checked && !airMailRadioButton.Checked && !nextDayRadioButton.Checked) return;

            //get the values out of the 2 text boxes
            int width = int.Parse(widthTextBox.Text);
            int height = int.Parse(heightTextBox.Text);

             //get the volume of package
            double volume = width * height;

            double totalCost = doingMath(volume);

            printResults(totalCost);
        }


        private double doingMath( double volume )
        {
            //figure out the total cost of shipping by using the shipping multiplier provided by Bob
            double totalCost = 0.0;
            if (groundRadioButton.Checked) totalCost = volume * .15;
            else if (airMailRadioButton.Checked) totalCost = volume * .25;
            else if (nextDayRadioButton.Checked) totalCost = volume * .45;
            else totalCost = 0.0;
            return totalCost;
        }
        private void printResults( double totalCost )
        {
            //print out the final result
            resultLabel.Text = String.Format("The Total Cost is: {0:C}", totalCost);
        }

    }
}