I was recently blown away by the Kaktovik numerals developed by Iñupiat middle school students in 1994, which make arithmetic much easier and are base-20:
https://en.wikipedia.org/wiki/Kaktovik_numerals
Another indigenous group, the Maya, used a similar base-20 system:
https://en.wikipedia.org/wiki/Maya_numerals
I'm thinking of applying something like these to a base-12 system for a language I'm playing with, though base-60 isn't looking bad either (used by the Sumerians among others):
https://en.wikipedia.org/wiki/Sexagesimal
#numerals #math #base20