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**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.

**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.

**John D. Barrow**challenges readers to estimate the errors that aren't found from the errors that are.

*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.