In French, the number system can be very different.
The number system is like ours, with variations of the digits for the 10’s (trente=30, trois=3; quarante=40, quatre=4), then tacking on the digit to the end to show exactly what number it is. (quarante-trois=43, quarante=40, trois=3). This is consistent until the 60’s (soixante).
7 is sept. You would expect 70 to be a variation of sept, like septante or something. However, 70 is actually soixante-dix (soixante=60, dix=10, the logic is that 70=60+10 or soixante+dix). And then you have to add the teen numbers to the end instead of individual digits (the teens don’t actually contain “teen” in French, obviously) to show the exact number.
so on (63-69)
so on (73-79)
That’s right. 80 is actually a combo of 4 and 20 (because they have to include multiplication), then 90 is quatre-vingt-dix (yay, even longer words!) 99 is a mouthful (quatre-vingt-dix-neuf), and larger numbers like 399 is even worse (trois cent quatre vignt dix neuf). French is much different from English, but it’s a pretty cool language.