<p>As best I can tell, this year about 70 started math 25 and the attendees are now around 35. This includes the refugees from 55 so assuming half the class does only the problem set and doesn’t show about 50 in the original math 25 class moved down to 23 or 21. I don’t know why somebody who does not have a serious abstract interest in mathematics would do either 25 or 55 cold turkey i.e., without any experience with proofs at all. If you are thinking off it, the ideal preparation it seems to me is Canada/USA mathcamp. BC calculus is not even an overture to either class. For the ordinary very good BC student, if you are still standing up in math 25 after 3 weeks you’re doing ok, if you pull a B- in the problem sets you are phenomenal. math 25 is like being nr 5 or ten in the olympics. No bragging rights but still 5th or 10th best in the world. Definitely not for the faint of heart.</p>