We use WAMAP for our practice problems. You will need to register (once) to use the practice problems. This is free and easy.
To register for the Practice Problems:
After you have completed this process, WAMAP will take you back to the login page.
Then you will need to enroll in the Practice Review Problems course (this is still free, and nobody is actually teaching this course).
Then click on the course name. If you have never used WAMAP before, you should probably start with "How to Use WAMAP."
After you have registered for the course, simply go to wamap.org, log in, and click on the course. Your registration might expire after a few months, but you can always reregister (same course ID and enrollment key).