To find the number of units between two points on a number line, you need to calculate the absolute difference between the two points. In this case, the points are (-3, -6) and (-3, -4).
First, find the absolute difference in the y-coordinates (vertical distance):
|-6 - (-4)| = |-6 + 4| = | -2 | = 2
The absolute difference in the y-coordinates is 2 units. Therefore, there are 2 units between the points (-3, -6) and (-3, -4) on the number line.
