good ol Firsteen and Seconteen. :)
It’s because of the base twelve counting system invented by Alexander P. Doodlenbottom. He didn’t like base 10 because it is more consistent and easier for people to learn. (That goes for any language affected like German where we have “Elf” and “Zwölf” instead of “Einzwen” and “Zweizehn”)

for example, it causes people to think adolescence begins right at 13 just because the word ends with ‘-teen’ when it actually starts at age *12*. Yes guys.. 12. Look it up on CDC gov! “Young Adolescence 12-14″ That is among many. I notice from working with kids that most of the changes appear at 12.

Well at least we dont have the counting problem in SPANISH (the “-teen” equivalent starts at 16. “once”, “doce”, “trece”, etc up to “diecisiete”..

On this point, I think I can safely say that Japanese is perfectly logical. You count one through ten, and then it is:
ten-one, ten-two, ten-three, etc. and following ten-nine comes
two-ten.
This is followed by
two-ten-one, two-ten-two, two-ten-three and so on. This pattern continues though nine-ten-nine, and then
hundred.
The hundreds follow the same pattern to thousand. Then after the number nine-thousand-nine-hundred-nine-ten-nine, the next number is (sorry, no English equivalent, but the unit is pronounced “man” and means 10000).
And on and on. No exceptions.

70 – soixante-dix (sixty-ten)
71 – soixante-onze (sixty-eleven)
72 – soixante-douze (sixty-twelve)
…
79 – soixante-dix-neuf (sixty-nineteen)
80 – quatre-vingts (four-twenties)
81 – quatre-vingt-un (four-twenty-one)
82 – quatre-vingt-deux (four-twenty-two)
…
90 – quatre-vingt-dix (four-twenty-ten)
91 – quatre-vingt-onze (four-twenty-eleven)
92 – quatre-vingt-douze (four-twenty-twelve)
…
99 – quatre-vingt-dix-neuf (four-twenty-nineteen)

You on a scale from 1 to 10. :)