French numbers are not very difficult to learn: they follow a similar pattern to naming numbers in English.
However, there are a few little quirks to French numbering that you should be aware of.
- 21, 31, 41, etc: numbers like these that end in 1 (excluding 81, probably because it’s so many words already) are said with an et-un at the end, not just un. All the other numbers are just like how we say them in English, such as vingt-trois (twenty-three) not “vingt-et-trois” (twenty-and-three).
- 70: Poor seventy doesn’t get its own word in traditional French (though other French-speaking nations use the word “septante“); instead, it’s called, literally, sixty-ten. From 71-79, the numbers follow this same pattern: soixante-onze for 71, soixante-douze for 72, etc.
- 80-99: Again, the numbers 80 and 90 both get neglected and don’t get their own words in French. 80, quatre-vingts, is literally “four-twenties” and 90, quatre-vingt-dix is “four-twenties-ten.” (Other French-speaking nations may use “huitante” for 80 and “nonante” for 90.)
- Be careful with the numbers for “billion” and “trillion” in French. For American English, where one billion is 1,000,000,000 and one trillion is 1,000,000,000,000, these need to be thought of in reverse: one “billion” is un milliard, and one “trillion” is un billion. (In UK English this is switched around, so the French words make sense if you speak British English. )