After all these years in Paris, I still have a hard time with French numbers. That's because the French, unlike other French speakers, for example in Belgium or Switzerland, still use the "score," as in "four-score-and-seven years ago...."
75 = sixty-and-fifteen (Do you see a seven in that?)
98 = four-twenties-and-eighteen (Do you see a nine in that?)
Even French people always hesitate just a fraction of a second when writing these. And when you think that telephone numbers in France are always given as, for example,
you see why we anglophones still have trouble writing that as fast as they say it.
Honestly, I don't know how they do math.
*0̶1̶.̶4̶2̶.̶7̶2̶.̶9̶4̶.̶9̶2̶ ̶ 01.42.73.94.92 (just a random Paris number I picked, sorry if it's yours!)