# Kops Make Great Theft Prevention Experts
Kops Make Great Theft Prevention Experts is a NetHack-themed mnemonic for prefixes from SI units of measurement (commonly called the metric system).
The mnemonic Kops Make Great Theft Prevention Experts is to memorise the order of of prefixes for every third power of ten from 3 to 18:

kilo-
Mega-
Giga-
Tera-
Peta-
Exa-

103
106
109
1012
1015
1018

Incidentally, the mnemonic is flawed. During actual gameplay, Keystone Kops do not appear until after you rob a shop. Thus they do not actually prevent the theft, they only react to it. The shopkeeper, by blocking the door, is actually the best theft prevention expert.