Approximate multiple:

(1) greatest common divisor least common multiple (2) Rules for judging the number of factories (the content of junior high school students' common test)

Composite number of prime numbers:

(1) Concepts and Judgments of Prime Numbers and Composite Numbers (II) Decomposition of Prime Factors (Emphasis)

Remaining problems:

Understanding and application of (1) formula with remainder: (2) The nature and application of congruence; (3) parity of China's remainder theorem: (1) parity and four operations; (2) Application of parity in practical problem solving: (1) Judgment and properties of perfect square number (2) Application of perfect square number, decomposition and splitting of integer and fraction (key and difficult points)

Divisibility problem:

The divisible characteristics and properties of (1) numbers (the content of Xiao Sheng's periodic examination)

(2) the application of the bit value principle (using letters and numbers to represent multiple numbers)

Number, line, shape and calculation, that is, number theory, line, diagram and calculation. So to what extent do we need to master these four questions?

The difficulty of number theory lies in abstraction, which is the key to distinguish top students from ordinary students; The complexity of travel problem lies in its application. Children do this kind of problem, not only need to think, but also need to express. Graphic problem (geometric problem) is complex and difficult, and the key requirement is the calculation of area, which is the beginning of middle school education; Calculation is the foundation and the necessary guarantee for children to get high marks.

The above four problems make students easy to get started, but they are not skilled and often make mistakes, so they have become the focus of key middle school exams in recent years. It is understood that these big questions in key middle schools account for about 80% of all the questions in recent years, and the investigation of these questions is also biased, while the investigation of number theory and itinerary is the most important, often accounting for 50% of a test paper. It is suggested that candidates who prepare for junior high school mathematics must pay enough attention to it.

;