Do all rulers have cm markers?

Answer by  kent16 (178)

No. Technically rulers don't have any markers because they are only used to draw straight lines. However, common usage is that the straight edge is marked to measure distance. The spacing of measurements can be metric (millimeters, centimeters, etc,), English (inches, feet, yards, etc), and some have both

Answer by  cielo (37)

While most rulers have length markers, certain ones known as straightedge rulers do not have any units of measurement marked on them. These types of rulers are use in geometry.