Wed, Dec 21 2011 at 10:09 PM
Decimate isn't restricted to powers of ten, it's a verb and not a unit of measurement.
verb (used with object), -mat·ed, -mat·ing.
1. to destroy a great number or proportion of: The population was decimated by a plague.
2. to select by lot and kill every tenth person of.
3. Obsolete . to take a tenth of or from.