Units are the cheat code to every physics/chemistry test. Once you know the units of your "known" you can usually derive almost any equation from simple logic. At a minimum it will get you close enough that you can remember the rest if you studied at least a little bit.
I just walked an organic chemistry student through hat on a fairly tough problem. Just showed them how every unit for every known can infer an equation, and all those equations for all your known will either get you to a complete system of equations to derive your needed formula, or will at least get you most of the way there and you can fill in the rest with a bit of logic).
It worked, we were trying to calculate morality for an acid when only the percentage by weight is given
.
@johnabs Good job!
@freemo Gotcha, just wanted to double check what units since the typo was ambiguous.
I used to teach dimensional analysis problems from the perspective of baking/buying stuff, and I got some of my nursing/agriculture students working out estimates mentally pretty quickly! It improved one girl's test scores by a whole letter grade after the tutoring sessions, so I took that as a win :)