Numbers one to ten

The numbers one to ten are among the most useful words you can carry into a Latin text or inscription: dates, ages, legion numbers, and prices all rest on them. Many are the ancestors of English words, so they double as a memory aid.

Numeral	Latin word	English echo
I	unus	unit, union
II	duo	duo, dual
III	tres	trio, triple
IV	quattuor	quart, quatrain
V	quinque	quintet
VI	sex	sextet
VII	septem	September (7th month)
VIII	octo	octopus, October
IX	novem	November
X	decem	decimal, decade

Examples:

• Tres pueri in via sunt. = Three boys are in the street.
• Decem annos habeo. = I am ten years old (literally, I have ten years).
• Legio quinta. = The Fifth Legion.

For English speakers: a small trap is that most of these numbers do not change their endings. Quattuor through decem are indeclinable, so you will not see the case endings you have learned elsewhere: this is normal, not an error. Only unus, duo, and tres shift form (for example duo, duae, duo and tres, tria). Also note the Roman practice of subtraction in numerals: IV is 4 (one before five) and IX is 9 (one before ten), not 6 and 11.