What is 1-1+1-1+1-1+...? How infinite sums challenge our notion of arithmetic.

Usain Bolt, the "fastest man on the planet", aims to get his 100 metre world record of 9.58 seconds down to 9.40 seconds. What has mathematics got to say about this quest?

Are records predictable in any way?

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.

Infinite series occupy a central and important place in mathematics. C. J. Sangwin shows us how eighteenth-century mathematician Leonhard Euler solved one of the foremost infinite series problems of his day.