## Articles

**David Spiegelhalter**and

**Mike Pearson**investigate.

**Martino Barenco**and

**Mike Hubank**shed light on suicidal cells and a mathematical model that could help fight cancer.

**Colva Roney-Dougal**and

**Vincent Vatter**explain, taking us on a journey from waiters sorting pancakes, via one of the richest men in the world, to the genetic similarities of mice and humans.

**Burkard Polster**and

**Marty Ross'**method for working out the day on which someone was born from their birthday really fast.

*x*

^{k}? If you're up to speed with your calculus, you can probably rattle the answer off by heart. But can you prove it?

**Chris Sangwin**introduces an ingenious method for deriving the integral from first principles.

*x*

^{k}really the best one?

**Chris Sangwin**makes an interesting case that it is not.