400 questions are simulation questions. This is just an estimate. To tell the truth, 400 questions are unnecessary. The topic is too difficult. Of course, your 400 questions can reach 120. You can get the real questions at 140. 660 questions are ok. Actually, it's not 660 questions This is 800 questions, all of which are fill-in-the-blank questions. The most important thing in postgraduate mathematics is the foundation. The whole book and the real questions are the most important.