Enrollment in Math 100 is not a prerequisite for any math class. It is the final exam for these classes which can place you into your next math class. You must take your final exam and score sufficiently high to place into your next math class.
Final exam/placement scores are loaded into the system within 3-5 business days of taking the final exam. You will be able to register for the Math class you are eligible for once your score is posted to the system. You can check the status of your posting at http://math.arizona.edu/academics/placement/exams/scores (if your Math 100 score is posted, you'll see an MCLG score, and approximate date of your final exam).