**The Joy of X**

Steven Strogatz

Houghton Miffli Harcourt, 2012 ($27)

Strogatz, an applied mathematician at Cornell University and author of *Sync*, has compiled his immensely popular series of *New York Times* columns and added new material. *The Joy of X*'s six parts, each divided into several short chapters, move from number basics through algebra, geometry, calculus and statistics to the frontiers of math, where conjectures about prime numbers are still floating around unsolved. The goal is a second chance at learning the math that might have passed you by—this time from an adult perspective. The tone is light and conversational, with delightful narratives about lonely numbers and the Tony Soprano psyche of math itself—outwardly tough but inwardly wracked with insecurity. The easily digestible chapters include plenty of helpful examples and illustrations. You'll never forget the Pythagorean theorem again! —*Evelyn Lamb*