@ZachWeinersmith

Not Saturday, but did just finish my Chex. I am neither of those but it seems to me that there is a difference between the concepts and the mechanics, the latter being where the calculator comes in. ~50 y/a, my parents swore I wouldn't always have a calculator in my pocket but ignore that.

Calculators aside, like times tables, there are probably a bunch of divisions anyone should be able to do in their head.

Good luck!