Exercise 7-1. Write a program with a Math class that has four methods: Add, Subtract, Multiply, and Divide, each of which takes two parameters. Call each method from Main( ) and provide an appropriate output statement to demonstrate that each method works. You don’t need to have the user provide input; just provide the two integers to the methods within Main( ).

Exercise 7-2. Modify the program from Exercise 7-1 so that you do not have to create an instance of Math to call the four methods. Call the four methods again from Main( ) to demonstrate that they work.

Exercise 7-3. Create a class Book that you could use to keep track of book objects. Each Book object should have a title, author, publisher, and ISBN (which should be a string, rather than a numeric type, so that the ISBN can start with a 0 or include an X). The class should have a DisplayBook( ) method to output that information to the console. In Main( ), create three Book objects with this data.

Programming C# 3.0     Jesse Liberty and Donald Xie        O'Reilly      9780596527433
C# 3.0 In a Nutshell   Joseph Albahari and Ben Albahari    O'Reilly      9780596527570
C# 3.0 Cookbook        Jay Hilyard and Stephen Teilhet     O'Reilly      9780596516109

Because all three books have the same publisher, you should initialize that field in your class.

Exercise 7-4. You might think it isn’t possible to draw geometric shapes using the console output, and you’d be mostly right. We can simulate drawing shapes, though, by imagining a graph and displaying, say, the coordinates of the four corners of a square. Start with a class called Point. This is a simple enough class; it should have members for an x coordinate and a y coordinate, a constructor, and a method for displaying the coordinates in the form (x,y). For now, make the x and y members public, to keep things simple.

Now create a class Square. Internally, the class should keep track of all four points of the square, but in the constructor, you should accept just a single Point and a length (make it an integer, to keep it simple). You should also have a method to output the coordinates of all four points. In Main( ), create the initial Point, then create a Square and output its corners.