French has some weirdness to its counting. 11 - 16 is specific words, 17 - 19 is "ten {number}" (dix-sept, dix-huit, dix-neuf).
There's also some fun when you get to 70... which is soixante-dix (sixty ten)... and 80 which is quatre-vingts (four twenties)... and 90 as quatre-vingt-dix (four twenties ten).
Some dialects of French outside of France have changed how they count.
With Spanish being similar with distinct words for 11-15 with 16-19 being 10+number. Taking Spanish in high school made me consider that for the first time while never having thought about 11,12 being similar in English until that same thought process.
Latin has 1 to 10 as quite reasonable. 11 is "undecim" (one ten), and 12 is "duodecim" (two ten)... 16 is "sedecim" (six ten), 17 is "septendecim" (seven ten)...
18 is duodeviginti (two from twenty) and 19 is undeviginti (one from twenty).
Yes, there are lots weird remnants of the vigesimal system around in French. You can see it in names like the Quinze-Vingts hospital - literally "fifteen twenties" because it was designed to have 300 beds.
