Lucky number 7. When asked to pick a number from one to ten, a really good first guess is the number seven.
I can’t remember where I first heard this, maybe in an article or a podcast where mathematician Alex Bellos was a topic or a guest, but here’s what rings true for me:
Numbers 1-10 are significant for humans because we’ve got 10 fingers on our hands. Of those, excluding multiples of 1 (which doesn’t really feel like multiplying, does it?), seven is the only number that is neither a factor not a product of any of the other numbers under ten. So in that important regard, it stands apart.
I think we know this intuitively. And that it’s the idea of seven that is special, rather than the mark that we recognize as representing that idea.
If we ever encounter an alien race with a different base four their counting system, rather than a base-9+1 (every counting system is base-10, why do we call ours that?) I’m sure they’ll have a different number that they consider the best/luckiest/superlative number.