Moebius bagels, Euclid's flourless chocolate cake and apple pi - this is maths, but not as you know it. In How to Bake Pi, mathematical crusader and star baker Eugenia Cheng has rustled up a batch of delicious culinary insights into everything from simple numeracy to category theory ('the mathematics of mathematics'), via Fermat, Poincare and Riemann. Maths is much more than simultaneous equations and pr2 : it is an incredibly powerful tool for thinking about the world around us.And once you learn how to think mathematically, you'll never think about anything - cakes, custard, bagels or doughnuts; not to mention fruit crumble, kitchen clutter and Yorkshire puddings - the same way again. Stuffed with moreish puzzles and topped with a generous dusting of wit and charm, How to Bake Pi is a foolproof recipe for a mathematical feast. *Previously published under the title Cakes, Custard & Category Theory*