Quatre-vingt-dix?! Why are some French numbers like this?
From 20-60, the French naming conventions all make sense and then there's soixante dix (70), quatre-vingt (80), and quatre-vingt-dix (90). Why not septante, huitante, and neufante (or something similar)?
I assume there's a logical reason for this that I just don't know.
Don't worry, the "regular" numbers septante, huitante and nonante do exist, but they're used only in Belgium and Switzerland.
The reasons these weird-looking compound numbers are used in France dates back to the Celtic people who inhabited France before the Roman conquest, and used a base 20 system instead of our base 10 system. For instance 80 is quatre-vings (4x20), 90 is quatre-vingt-dix (4x20+10)...
This Celtic system was gradually replaced by the Latin base 10 system almost entirely, except for large numbers (above 70) because they were used less often.
I think it's just to make the rest of us non-French speaking people crazy.
Exactly, for us, evil Frenchies, we do not have a mad hatter nor a caterpillar that becomes invisible, so we take revenge with numbers "abracadabrantesques" and "croquignolesques".
abracadabrantesque et croquignolesque sont des adjectifs que les présidents de la République française adorent utiliser dans leurs discours.
And also, the little French schoolchildren have great difficulties to understand why we have to write "soixante-dix" but not "cinquante-dix".
It's just how it is. You'll get used to it. However, these numbers are said differently in the French-speaking parts in Switzerland. Septante for seventy and nonante for ninety. The Swiss think this is more logical. However, eighty is the same as in France.
I was told this numbering system is similar to that used by Abraham Lincoln in his Gettysburg address. Instead of saying 87 years ago, he said "four score and seven" years ago. Apparently that use was not uncommon once upon a time in England and on the continent.