In fact, the mathematical knowledge we learned in school has really reached the society, which may be of little use or even useless, but what we have learned in our study is not only mathematical knowledge, but more importantly, mathematical thinking, mathematical thinking mode and mathematical space imagination, which are all imperceptibly learned in the learning process (you may not realize that you have mastered these knowledge), and it is precisely this knowledge that affects our ability to be a person, do things and socialize. Of course, if you need to apply this knowledge to your work, you need to review it again. There is no clever way. Ha ha!