"Nothing is more interesting than nothing" — or so says Ian Stewart, Professor of Mathematics at Warwick University. Many people have difficulty with the concept of zero. In fact, it has only really been used *as a number* for the last 1500 years or so. Before this time it seems that zero was simply not that important. At the end of the day, a herd of no camels is not worth much.

Perhaps our ancestors were better off? Once you start using zero as a number then you can easily get into difficulty. Adding and taking away don't cause too much trouble, multiplication is straightforward (though a little unrewarding) but division simply has to be disallowed.

In a previous issue of PASS Maths we were asked what *infinity* multiplied by zero was. Our answer was that *infinity* cannot be multiplied by anything in the usual sense of the word because it is not a number. It's harder to explain away one divided by zero because they're both numbers; you're simply not allowed to do it.