Even if you've only been studying French half-heartedly until now, you will probably have encountered lessons on French numbers. Most of us are pretty comfortable with un, deux, trois, quatre... so the following table will come as no shock to you! It represents the general way to form numbers.
Pay attention to the number 21 (vingt et un) in which the "one" is attached like "twenty and one" as opposed to 22 (vingt-deux), 23 (vingt-trois) and so forth.
Be sure to listen to the audio that follows, since pronunciation can be a lot different to what you'd expect!
We said things get a little more difficult past number 70. Here's what we mean:
Right about number 70, our numbers switch from being base-ten (like in English) to being base-twenty. So instead of "seventy" being "seventy", it's called "sixty-ten". Seventy-two is called "sixty-twelve".
It might be a little confusing, but at least it means you don't have to remember another number — just recycle the ones you've learned already!
That's not the end of things. The 80s and 90s bring more confusion.
It gets even more confusing if you venture into any other French-speaking countries: In Belgium and Switzerland they use septante (seventy) instead of soixante-dix (sixty-ten) and nonante (ninety) instead of quatre-vingt-dix (four-twenty-ten). In Switzerland (but not in Belgium) they also use huitante for eighty, instead of quatre-vingts.
If this all seems too confusing for you, just stick with the French-French numbers we've outlined below. Regardless of which country you visit, these numbers will always be understood, even if they're not conventionally used.