In this episode we watch the movie Proof. Did Gwyneth Paltrow really prove the theorem? What theorem was she trying to prove? How many vaginas does a Time Lord have? All these questions and more are discussed in this weeks Maths at the Movies. If you're interested in watching Proof you can follow the Amazon link below. Further reading links: more about the amazing life of Sophie Germain; who was Erdos?; calculate your Erdos number; what are prime numbers good for?; the ideas behind the Four Colour Theorem; buy the book of the play. Subscribe via iTunes.