CD Publisher
 In this exercise, we will develop an application for a small CD publishing company. The owner wants the prices to be calculated so a customer would get a discount if he orders more. To attract customers and encourage them to order more, she has decided to fix the prices so that the customer would pay: \$20/CD if he orders less than 20 units \$15/CD if he orders less than 50 units \$12/CD if he orders less than 100 units \$8/CD if he orders less than 500 units \$5/CD if he orders more than 500 units
1. Start Visual Studio
2. Create a new Visual Basic Windows Application and name it CDPublisher
3. Design the form as follows:

 Control Name Text Other Properties Label Number of CDs: NumericUpDown updQuantity Maximum: 10000 TextAlign: Center Label Unit Price: TextBox txtUnitPrice 0 TextAlign: Right Label Total Price: TextBox txtTotalPrice 0 TextAlign: Right Button btnClose Close
4. Double-click the Close button and implement it as follows:

 ```private void btnClose_Click (Object sender, System.EventArgs e) { Close(); }```
5. Double-click the up down button to access its OnChange() event and implement it as follows:

 ```private void updQuantity_ValueChanged (Object sender, System.EventArgs e) { int Quantity; double UnitPrice, TotalPrice; Quantity = System.Convert.ToInt32(updQuantity.get_Value()); if( Quantity < 20 ) UnitPrice = 20; else if( Quantity < 50 ) UnitPrice = 15; else if( Quantity < 100 ) UnitPrice = 12; else if( Quantity < 500 ) UnitPrice = 8; else UnitPrice = 5; TotalPrice = Quantity * UnitPrice; txtUnitPrice.set_Text(String.Format("{0:C}", (System.Double)UnitPrice)); txtTotalPrice.set_Text(String.Format("{0:C}", (System.Double)TotalPrice)); }```
6. Test the application
7. Close it