Want facts and want them fast? Our Maths in a minute series explores key mathematical concepts in just a few words. From symmetry to Euclid's axioms, and from binary numbers to the prosecutor's fallacy, learn some maths without too much effort.
Euclid's fourth axiom says that all right angles are equal. But isn't that obvious?
The Indian way of adding fractions makes things easier (with musical explanation).
How to lose a spacecraft in the most embarrassing way possible.
Are there more irrational numbers than rational numbers, or more rational numbers than irrational numbers? Well, there are infinitely many of both, so the question doesn't make sense. It turns out, however, that the set of rational numbers is infinite in a very different way from the set of irrational numbers.