adopted in anticipation of needs for use in data science, and because unofficial prefixes that did not meet SI requirements were already circulating. The small prefixes were also added, even without such a driver, in order to maintain symmetry.

The prefixes from peta to quetta are based on the Ancient Greek or Ancient Latin numbers from 5 to 10, referring to the 5th through 10th powers of 10³. The initial letter h has been removed from some of these stems and the initial letters z, y, r, and q have been added, ascending in