Cake? Yum. Algebra? Pass. Not so fast—baking requires more number crunching than you think. Enter the delicious world of math—not head-scratching lectures but useful, digestible info, as taught by mathematics professor Dr. Eugenia Cheng. She channels her love of cooking into the up-tempo How to Bake Pi ($28)—which you should add to your bookshelf.

Price: $27.50