Despite an applied maths degree and a career in informatics, TIL that C is Clear Everything and CE is Clear Entry. Naively, I always assumed the opposite.
Some scientific calculators have a button marked AC for "all clear", also sometimes in a distinctive color so you know it's important. Features like that appear aimed at people like you and me, who aren't specially trained in calculator use and have to reacquire familiarity with what the buttons do when we use the machine upon occasion.
To be fair: if it was aimed at people who don't use desk calculators all day, maybe it should say "clear all". You know, in actual words. Or have a picture of a trash can on it. To me, desk calculators with CA/M/MR/MC... are a design fail.
Chording them together means “fuck it”
An early form of control-alt-delete.
Alt+hold F4
which will bring you a loop of a "save before quit?" dialog and then killing it :D
It’s been a while since I used a calculator, but yeah. I know that the M-buttons do some storage from when I learned about it in high school, but that was a long time ago.