Elements of the 1. axis: positive direction (indicated by arrow), origin (0 scale) and unit length (scale).
Positive direction: according to the meaning of the question, the positive direction is determined, generally upward or right.
Origin: that is, the position of the number 0 is generally determined according to the distribution of the number. If the positive and negative numbers to be represented are almost equal, the origin is in the middle of the number axis; If there are more positive numbers than negative numbers, the origin is left; If there are more negative numbers than positive numbers, the origin is on the right.
Unit length: the distance between scales is determined by the size of the number to be represented. If the quantity is too large, the scale distance can be appropriately smaller, if the quantity is too small, the scale distance can be appropriately larger. The unit length is not necessarily 1 for each scale.
2. Use the number axis to represent numbers.
Represents a number on a given axis: tracks a point on the corresponding scale according to the number.
For the representation of non-integers: further subdivide the scale. For example, if the line segment between 0 and 1 needs to be divided into three equal parts, then the number will be found in two equal parts.
For negative numbers, it means that negative numbers are all on the left of 0 and positive numbers are all on the right of 0. For example, +3.5 is between 3 and 4, and -3.5 is between -3 and -4.
3. Compare numbers according to the number axis.
All positive numbers are greater than negative numbers; All negative numbers are less than positive numbers.
The numbers on the left of 0 are all negative, and the numbers on the right of 0 are all positive;
On the number axis, the more numbers on the right, the smaller the numbers on the left;
Negative number comparison, regardless of the negative sign, the number of large numbers is small;
0 is greater than all negative numbers and less than all positive numbers. negative number