1 and numbers greater than 0 are called positive numbers.

2. Numbers preceded by minus sign "-"are called negative numbers. ?

3. Integers and fractions are collectively called rational numbers. ?

People usually use points on a straight line to represent numbers. This straight line is called the number axis. ?

5. Take any point on the straight line to represent the number 0. This point is called the origin.

6. Usually, the distance between the point representing the number A on the number axis and the origin is called the absolute value of the number A ...?

7. From the definition of absolute value, we can know that the absolute value of a positive number is itself; The absolute value of a negative number is its reciprocal; The absolute value of 0 is 0. ?

8. Positive numbers are greater than 0, 0 is greater than negative numbers, and positive numbers are greater than negative numbers. ?

9, two negative numbers, the absolute value is big but small. ?

10, in rational number addition, two numbers are added, the addend positions are exchanged, and the sum is unchanged. ?

1 1. rational number addition, three numbers are added, the first two numbers are added first, or the last two numbers are added first, and the sum is unchanged.

12, rational number subtraction rule: subtracting a number is equal to adding the reciprocal of this number. ?

Mind mapping, also known as mind mapping, is an effective graphic thinking tool to express divergent thinking. It is simple, effective and efficient, and it is a practical thinking tool. Mind mapping uses the skills of paying equal attention to graphics and texts, showing the relationship between topics at all levels with hierarchical diagrams of mutual subordination and correlation, and establishing memory links between topic keywords, images and colors. ?