It's one of mathematics' most famous results: every "map" can be coloured using at most four colours. What it doesn't usually apply to, however, are real maps.
This puzzle is famous because the accepted answer is counter-intuitive. But is it always correct?
The golden ratio has many amazing properties. But is it really a secret of nature and the epitome of beauty?
With just a few months to go until the UEFA European Cup, here's how you can make your office sweepstake a lot fairer and more exciting.
Nothing, not even light, can escape from a black hole. Or can it? Find out about one of Stephen Hawking's most radical results.
Explore a mystery that intrigued Stephen Hawking until the end of his life.
Nobody has ever found an odd perfect number. So do they exist at all and, if yes, what do they look like?
The answer comes from the physics of waves.