For devotees of recreational mathematics, Tim Sole presents 28 numbers, starting with .301 (concerning Newcomb’s formula for the proportion of naturally occurring numbers beginning with the digit N) and ending ‘Beyond Infinity’ with Cantor’s amazing discovery that there are an infinite number of numbers bigger than infinity. Among chapters on topics such as the fundamental constant of music (1.059) and Euler’s identity, there are 38 conundrums (with answers) for the mathematically inclined.