Counting in French, why is it so complicated ??

A nice mix of decimal and vigesimal systems. But how did we get here? So, the French are over-gifted in math.....non?
I'm talking about base 10, base 20, money, vocabulary in France, Switzerland and Belgium and, of course, history.
My name is Sebastien, I'm a French teacher and I like to learn about the evolution of the language and why things are the way they are today.
To find out about my language courses: francaispourexpats.com/
And here too: / francaispourexpats
0:00 Intro
0:35 Decimal system
1:02 Base 20 system
1:30 In other languages
2:27 Money
3:15 Back to base 10
4:11 In Switzerland and Belgium
4:20 Strong in math?

[@jthillerup]

You have the same in danish language where 80 is called “firs" which is an abbreviation of four times twenty (fire sinde tyve)

[@FrancaisPourExpats]

That's right, it's not a French exclusivity. Other languages have these similar roots. Thanks for the input.

[@stephanobarbosa5805]

Septante Huitante Nonante