You don’t need to be smart. Back in my uni, there were student initiatives to record the questions and answers of previous exams. The Math department itself gave out previous years exams to study from.

The key to remember: exams aren’t written my professors, they’re written by the postdocs who have better things to do, and so they just rehash the same stuff from the year before.

If you want to get a useless piece of paper that tells you that you are an expert in topic X, then don’t learn X, learn to pass the papers for the X exam, and learn X later in your free time if you’re still interested in it.