Math formula and theorem reference

Start from the problem, not the formula name

If you already know you need the law of cosines, go straight to its page. If you are staring at a triangle with two sides and the angle between them, the topic listing is faster — the formulas are grouped by the situation they answer, not alphabetically.

Each page ends with related formulas, which is usually where the actual answer lives when the first one nearly fits.

The symbol table is the part people skip

Most wrong answers from a correct formula come from reading a symbol as the wrong thing: r as diameter, n as the number of years rather than the number of compounding periods, θ in degrees where the formula wants radians. Every page lists each symbol with the units and the sign convention, because that is where the error actually happens.

Pages appear as their content is written

A formula with nothing but a statement and an empty table is not a page worth publishing, so it is not published. Entries go live once they have worked examples, common mistakes and an FAQ that were written and then reviewed by a person.