## Articles

*Plus*talks to the Government Actuary, Chris Daykin about the

**pensions crisis**, and how actuaries use statistical and modelling techniques to plan for all our futures.

**Riemann Hypothesis**is probably the hardest unsolved problem in all of mathematics, and one of the most important. It has to do with prime numbers - the building blocks of arithmetic. Nick Mee, together with Sir Arthur C. Clarke, tells us about the patterns hiding inside numbers.

- Optional maths - should students be able to give up maths at age 14?
- Outer space - In what will now be a regular feature, mathematician and cosmologist John D. Barrow shares some maths that's amused and intrigued him.
- Readers' corner- More Strange activities for last issue's Ship of Fools!

**mathematical modelling**.

**Navier-Stokes equations**.

**grand mathematical challenges**of the 21st century. But be warned...these problems are hard. In the first of two articles, Chris Budd explains how to hit the bigtime.

*Plus*finds out about the role of mathematical

**symmetry in chemistry**.