You might enjoy https://math.ucr.edu/home//baez/torsors.html

Also https://www.youtube.com/watch?v=CfW845LNObM

Torsors!! I had never heard of them but it feels like I've wanted that page for years! Also an excellent 3B1B.

You cannot currently switch between multiplication and division (at least in Chrome), because disabling the fieldsets also disables the contained radios.

(Also, the number inputs are too narrow - they barely show more than one digit.)

made the inputs just a bit wider! switching between multiplication and division worked fine for me in chrome 99, even with the radio buttons in the legends of the fieldset — but i can imagine how that might be brittle/underspecified behavior lol so i just moved the radio buttons out of the fieldsets.