Human beings are famously prone to error, and proof-readers are, after all, only human. But who picks up the errors a proof-reader misses? John D. Barrow challenges readers to estimate the errors that aren't found from the errors that are.
The number chosen by the England captain for his Real Madrid shirt is rich in mysterious connotations. But mathematician Marcus du Sautoy backs a new theory to explain why Beckham has plumped for number 23.