AP Calculus BC Credit and Placement for LSA Freshman

Hi,

I try to understand how AP exams can help get credits and placements for LSA students, but I am not quite get it. Can anyone explain about this?

http://admissions.umich.edu/apply/freshmen-applicants/ap-ib-credit#LSA

For AP Calc BC, if you get a 4, you get credit for Calc 1, but if you get a 5, you get credit for both Calc 1 and 2. However, you are only awarded 2 credits for both classes. If you want to get full credit for them (which would be the 4 credits for both classes), you need to take an additional math class at a higher level.