Professor Zhang is indeed a kind person. His exams are more than fair. Number theory is not an easy thing to teach, especially to students with no background on it. He did a great job in introducing such new subject to the class. And he often asks the class about pacing, and he adjusts it if needed. Homework is difficult, but hints are given.

Decent lectures, though at times unorganized. Zhang was very kind, but at times he seemed annoyed at students' questions. Both his homework and exams were straightforward.