Final answer:
The ruler placement postulate states that you can measure the distance between two points by using one of the points as the zero on the ruler.
Step-by-step explanation:
The ruler placement postulate states that you can measure the distance between points A and B by using one of the points as the zero point on the ruler. For example, if you choose point A as the zero point, you can measure the distance from point A to point B by aligning point A with the zero mark on the ruler and reading the measurement at point B.