Finished part 3:
So, the workflow of the app is as follows. You can call any class (not interface) within my 'math' package. Once you have chosen a class you can then choose any method in that class. There are instructions inside the client that explain that you can pass  in a comma delimited list of numbers, and the functions will be executed on said list. Once you've chosen a class, you cannot back out and choose another; you can quit however.