Innumeracy: Mathematical Illiteracy and Its Consequences (John Allen Paulos)

This has become a classic. I read the first edition as a student back in 1990.

Why do even well-educated people understand so little about mathematics? And what are the costs of our innumeracy?

The author argues that our inability to deal rationally with very large numbers and the probabilities associated with them results in misinformed governmental policies, confused personal decisions, and an increased susceptibility to pseudoscience of all kinds. Innumeracy lets us know what we're missing, and how we can do something about it.

The topics covered range over many aspects of modern life, from contested elections to sports stats, from stock scams and newspaper psychics to diet and medical claims, sex discrimination, insurance, lotteries, and drug testing.

Highly recommended.