Numerical Prefixes

A prefix is a syllable at the beginning of a word. A numerical prefix lets you know how many there are of a particular thing. Here are some common numerical prefixes.

PrefixPrefix meaningSample words
uni-1unicorn: mythical creature with one horn
mono-1monorail: train that runs on one track
bi-2bicycle: two-wheeled vehicle
tri-3triceratops: three-horned dinosaur
quadr-4quadruped: four-footed animal
quint-5quintuplets: five babies born at a single birth
penta-5pentagon: figure with five sides
hex-6hexapod: having six legs, an insect, for example
sex-6sextet: group of six musicians
hept-7heptathlon: athletic contest with seven events
sept-7septuplets: seven babies at a single birth
octo-8octopus: sea creature with eight arms
novem-9novena: prayers said over nine days
deka- or deca-10decade: a period of 10 years
cent-hundredcentury: a period of 100 years
hecto-hundredhectogram: 100 grams
milli-thousandmillennium: a period of 1,000 years
kilo-thousandkilogram: 1,000 grams
mega-millionmegaton: one million tons
giga-billiongigawatt: one billion watts