Chapter 2: 1. The concepts of positive and negative numbers, and 0 is neither an integer nor a negative number.

2. Positive integers, negative integers and 0 are collectively called integers, positive and negative fractions are collectively called fractions, and integers and fractions are collectively called rational numbers.

3. Specify the origin and positive direction, and the straight line per unit length is called the number axis. The farther to the left, the smaller the number, and the farther to the right, the greater the absolute value of the number. Taking any point on a straight line means 0, which is called apogee.

4. The distance between a point on the number axis and the origin is called the absolute value of this number.

5. Of the two points on the number axis, the number represented by the right point is greater than that represented by the left point.

6. Two numbers with different signs and the same absolute value are opposite numbers, the opposite number of a positive number is less than the original number, and the opposite number of a negative number is greater than the original number.

7. The absolute value of a positive number is itself, the absolute value of a negative number is its reciprocal, and the absolute value of 0 is 0.

8. Rational number multiplication rule, two numbers are commensurate, the same sign is positive, and the different sign is negative.