Barbara Oakley

Flunked her way through school mathematics, joined the army, learned Russian, worked as a radio operator on a Soviet trawler, and then retrained as an engineering professor in her late twenties.

A Mind for Numbers is written for people who believe they are not maths people, and its core idea is borrowed from cognitive science: the brain has a focused mode and a diffuse mode, and learning happens when you alternate rather than grind. The companion course became one of the most enrolled online courses ever run.

The advice is unglamorous. Sleep, spaced practice, testing yourself, and stopping when stuck.