There are many different types of lottery around the world, but they all share a common aim: to make money. John Haigh explains why lotteries are the way they are.

In issue 29 of Plus, we heard how a simple mathematical equation became the subject of a debate in the UK parliament. Chris Budd and Chris Sangwin continue the story of the mighty quadratic equation.

Most magazines have endless articles and correspondence about relationships and you will be pleased to hear that Plus is now no different. Why?

Did you know that every instant, gravity waves from outer space are stretching and squeezing you - and everyone and everything else in the universe? Learning more about this mysterious radiation will help us to probe the structure and origins of the universe, explains Anita Barnes.

In the early days of the UK National Lottery, it was quite common to see newspaper articles that looked back on what numbers had recently been drawn, and attempted to identify certain numbers as "due" or "hot". Few such articles appear now, and John Haigh thinks that perhaps the publicity surrounding the lottery has enhanced the nation's numeracy.

It isn't often that a mathematical equation makes the national press, far less popular radio, or most astonishingly of all, is the subject of a debate in the UK parliament. However, as Chris Budd and Chris Sangwin tell us, in 2003 the good old quadratic equation, which we all learned about in school, reached these dizzy pinnacles of fame.

The concept of a speed limit seems a simple one - until you think what can happen when a speed camera clocks a rotating wheel...

A biologist has developed a blood test for detecting a certain minor abnormality in infants. Obviously if you have blood samples from 100 children, you could find out which children are affected by running 100 separate tests. But mathematicians are never satisfied by the obvious answer. Keith Ball uses information theory to explain how to cut down the number of tests significantly, by pooling samples of blood.

In 1997 Garry Kasparov, then World Champion, lost an entire chess match to the IBM supercomputer Deep Blue, and it is only a matter of time before the machines become absolutely unbeatable. But the human brain, as Lewis Dartnell explains, is still able to put up a good fight by exploiting computers' weaknesses.