Ha! I might have known back then, but it's also likely I made college harder for myself than necessary.
Yes, ROT13 (or maybe ROT47) might be enough to stymie lazy solution-seekers. Might do that here if an even-numbered exercise seems to warrant some discussion.
Just think of how much harder you made college for yourself.
Edit: to be serious, the solutions at the back (which I look forward to flipping to after every other exercise, kind of like a rat getting a food pellet in an experiment) are interesting in their own right. He plants little clues in there, to hint at what was important or why he asked the question.