To celebrate the release of more English translations of Einstein's papers, we revisit one of his previously unknown models of the Universe.
A Klein bottle can't hold any liquid because it doesn't have an inside. How do you construct this strange thing and why would you want to?
Anything involving bunny rabbits has to be good.
What is 1-1+1-1+1-1+...? How infinite sums challenge our notion of arithmetic.
How to write a sum that's infinitely long.
Here's an easy game that leads you straight to an unsolved question in maths.