It is, of course, the value of 9 and the margins of countless school maths books have been filled by generations of acned Einsteins eager to prove that they can add more digits to the right of the decimal point than anyone has ever done before.
The winner, as far as I can see, is Jeremy Gilbert who has managed to express the value of 9 to a respectable 2.5 million decimal places.
If you are not doing anything for the next few decades and fancy checking his answer, it's available in that great reservoir of useless information, the World Wide Web. There are dozens of pages devoted exclusively to 9. Here, mathaholics - as they cheerfully label themselves - study the digits, looking for patterns, oddities and, perhaps, the meaning of life. You'll find even more sites devoted to squaring the circle and even a few to Zeno - the genius who managed to prove that an arrow fired at a target, however fast it flies, will never reach it.
The mathaholics who visit the Web seem to have a penchant for knots, and are especially fond of the virtual variety - the sort that can only be tied using mathematical formulae rather than fingers and thumbs. Any self-respecting Scout would happily die for these impossibly intricate, computer-generated three dimensional creations, the best of which are exhibited at the Internet's Knot Zoo.
You don't need a working knowledge of Principia Mathematica to enjoy many of the sites that you find on the Web. Indeed children who relish doing sums will relish the opportunity to browse around.
They can discover, for example, that in a group of 23 people there is more than a 50 per cent chance that at least two of them share the same birthday. Or they can learn how easy it is to dissect a square into 38 smaller squares, all of different sizes. If they run into problems, they can e-mail Dr Math, Dr Calculus and an army of other egg-heads who are always ready to lend a helping hand.
There are also numerous on-line tutorials, puzzles, worksheets, competitions and those fascinating paradoxes that keep mathaholics awake at night.
Unfortunately too many our present generation of school pupils are unlikely to be able to reap the benefits. The results of the Third International Mathematics and Science Study reveal that when it comes to doing sums, English children came a depressing 17th in a league table of 26 countries, far behind Singapore, Korea, Japan and Hong Kong.
Ministers want to see a major improvement: by 2002, they want 75 per cent of 11-year-olds to reach an attainment target that only 55 per cent are achieving at the moment. Their proposed strategy - if the newspapers are to be believed - is more whole-class teaching, more time learning tables and a headlong rush back to basics.
It doesn't seem terribly exciting - especially for a government that has done its level best to equate New Labour with a new Britain - and with new technology. In fairness to ministers, they are faced with a paradox which would baffle even Dr Calculus. Children won't relish doing maths unless they find it fascinating. The Internet can reveal to them how fascinating it is.
But they can't benefit from the Internet unless they relish doing maths in the first place. I'm not sure how to describe the challenge that ministers face. They will either have to square the circle or cut a Gordian Knot. Which ever it is, the Internet, as usual, will prove an invaluable starting point.
Knot enthusiasts could start at: http:ww w.earlham.edusu
A good starting place for mathaholics: httpweb.arcos.orgsumfunINDEX. HTM