How to write a sum that's infinitely long.

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

Here's an easy game that leads you straight to an unsolved question in maths.

How to write down unimaginably large numbers using just a few symbols.

A little trig helps to find the relative distance to the Sun and Moon.

Bob Wald tells us why probabilities are important in cosmology.

Why maths is an important tool in the fight against Ebola.

Why do we add fractions the way we do? A very close look at addition reveals the answer — and it also works for negative numbers.

John D. Barrow tells us how to get the best view!

How to derive the famous quadratic formula from pictures, just like the Babylonians did.

Euclid's fourth axiom says that all right angles are equal. But isn't that obvious?

Five basic facts from the father of geometry.