Well, we have to hang up for 24 hours here, which means that all subjects (optional) add up to 24 hours to take the exam, but only if you choose a course and you have to hang up all the hours of the course to take the exam. For example, if you take the course "Accounting Professional Ethics", you have to listen to all the classes in the course before you can take the exam. If the course is 6 hours, you still need to take 18 after the exam.