“Life can make sense,” is the motto of this forthright little book, and all it takes is a little math. Shaffner, an executive in the computer industry, has taken a selection of the basic situations and decisions of day-to-day life and quantified them. The math is within the grasp of even the most number-shy: nothing more complex than percentages and division. Each short chapter addresses a basic question from everyday life: how much difference does staying in school make in a person’s income? What are the odds of getting caught speeding (or robbing a bank)? How much does it really cost to smoke cigarettes? In each chapter, Shaffner takes some raw data (e.g., the cost of a given federally funded project), and performs a simple calculation (division by the number of taxpayers) to arrive at the per-taxpayer cost of a given project, and then multiplies by the number of congressional representatives to show what it would cost if each of them were allowed one “pork barrel” project a year. Similar calculations are applied to everyday economics—for example to debunk the widely accepted principle that the top 20 percent of workers do 80 percent of the work or to show the necessity of middle management in large organizations (otherwise, top executives would have no time for their own jobs). Other chapters discuss fields where superficial logic often yields wrong results: simple calculation proves that even when 70 percent of the players at a “fair” gambling game are winners, the house still makes a tidy profit. Another shows how million-to-one “coincidences” can easily occur in a large enough sample. Written in lively style, with sly wit and plenty of examples from familiar areas of experience, the book offers an appealing mix of common sense and solid reasoning. Shines light into several interesting corners of everyday life, often with surprising results—and the numbers don’t lie.