I have no idea what was going on inside his head but he just couldn't figure out things like making change for a dollar. He and my roommate were doing their cal

I have no idea what was going on inside his head but he just couldn't figure out things like making change for a dollar. He and my roommate were doing their calculus homework shortly before he left and he just couldn't do simple problems. He went from just getting math to being mistified by it.