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 It is not uncommon for physics students to know more about the history of physics than mathematics students do about the history of mathematics. Physical laws often come with a name attached; mathematics constitutes a more homogenous structure, and thus tracing parentage can be harder. Of all the classical functions, the Gamma function still retains much of its mystery and intrigue, since Euler first spotted it as something "worthy of serious consideration". In Gamma, Julian Havil explores Gamma from its birth and in so doing simultaneously deals with many related functions, problems and issues that go beyond the conventional territory of functions alone. What is maths for? - What do we hope people will know after studying maths at school? New Plus posters! - Find out how you can get hold of your own copy of our brilliant new poster! Specially for students - This issue of Plus brings you the first of an occasional series expecially for use in the classroom. 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. Marcus du Sautoy begins a two part exploration of the greatest unsolved problem of mathematics: The Riemann Hypothesis. In the first part, we find out how the German mathematician Gauss, aged only 15, discovered the dice that Nature used to chose the primes. Skot McDonald talks to Plus about how he uses mathematics to understand music, and how he managed to combine his passions for music and computing to create a successful career. Calculus is a collection of tools, such as differentiation and integration, for solving problems in mathematics which involve "rates of change" and "areas". In the first of two articles aimed specially at students meeting calculus for the first time, Chris Sangwin tells us about these tools - without doubt, the some of the most important in all of mathematics. Not only are paper models of geometric shapes beautiful and intriguing, but they also allow us to visualise and understand some important geometric constructions. Konrad Polthier tells us about the gentle art of paper folding.