OK, this totally blew my mind, even though it shouldn’t have.
We tend to think that numbers are a universal language … But the way that humans actually use numbers – when we talk to each other – it is not really as universal as you might think.
We think that everyone would tend to use base-ten counting, since we have ten fingers, but we also have twelve finger bones per hand (14 if you include the thumb), and as Tom Scott points out there’s no need to restrict ourselves to our hands. I should have remembered about base-60 number systems, which are kind of everywhere.
It’s an important lesson in assumptions.