Confused by Mays Math Requirement

I just found some paperwork on the AP credit from way back when… it isn’t a misprint, my mistake Math 142 is the substitute of Math 151. Back in those days, they had you register for Math 141 if you took Calc AB… but not sure why? I just wrote it down as that being said at NSC, it was pre-AP scores being released, and many years ago. You probably already figured it out, but should someone else read this I wouldn’t want to lead them astray :wink: