Zeno and the Three Rulers

A student of Zeno was the proud owner of three rulers. One had gradations for inches only: 12 inches from end to end. The second had markings each half inch; this one was 24 half inches in length. The third had inches, half inches, and quarter inches all neatly inscribed, with a total of 48 quarter inch units. Still somehow all three rulers were the same length!