1. Four operations: addition, subtraction, multiplication and division are the most basic operations in mathematics competitions, which need to be mastered skillfully and used flexibly.

2. Integer and decimal: Understand the concepts of integer and decimal, and be able to add, subtract, multiply and divide.

3. Fractions and percentages: master the basic concepts and operation rules of fractions, and be able to add, subtract, multiply and divide fractions; Understand the concept of percentage and its relationship with score, and be able to convert and calculate percentage.

4. Algebraic expressions and equations: Understand the concept and basic operations of algebraic expressions, and be able to add, subtract, multiply and divide algebraic expressions; Mastering the solution of linear equation of one variable can solve the simple linear equation of one variable.

5. Geometry and space geometry: Understand the basic concepts and properties of plane geometry, such as lines, angles, triangles, quadrangles, etc. Understand the basic concepts and properties of space geometry, such as cubes, cuboids, cylinders, etc.

6. Data and statistics: Understand the methods of data collection, collation and analysis, and be able to make simple data statistics and charts.

7. Logical reasoning and problem solving: cultivate logical thinking ability and be able to use mathematical knowledge to solve practical problems.

In addition, participating in junior high school mathematics competition also requires good mathematical thinking ability, problem-solving skills and test-taking experience. Through a lot of practice and accumulation, you can improve your math level and get good grades in the competition.