Whether it is elementary mathematics or advanced mathematics, it is essential to practice the necessary questions. For elementary mathematics (which can be understood as the content learned in junior high school and senior high school), doing more and practicing more can cultivate mathematical thinking, and have fixed ideas for fixed problems, so that you can deal with problems easily and think quickly. In this process, it is inevitable to do wrong questions. Then doing the wrong question doesn't mean you can't do it, but it means that your thinking is wrong, your way of thinking is wrong, or you are not skilled in dealing with such problems. Doing wrong questions at this time is to correct these. So it is necessary to do wrong questions.