Compulsory 1-5, elective 2- 1, 2-2, 2-3 include elective 2-3, mainly statistics, counting principle and probability. "Compulsory Mathematics for Senior High School 3" is the third book in the compulsory series of senior high school mathematics in the new curriculum standard, which is divided into two versions, A and B, and published by People's Education Press. The main content of this book is to explain and summarize the knowledge of algorithms, statistics and probability.