It passes through our minds, it tumbles off our fingers every day. Regardless almost of our race or tongue, it is as close to us as the date of our birth, the number of our telephone, the house in which we live. Yet how often do we ever think of 9? In numbers, Pythagoras and Plotinus and other worthies have believed, lie the secrets of the universe; God and nature move in 40-day rotations, 28-day cycles, passages of 9 months. And in 9 alone is a universe -- maybe even a paradise -- if only we would stop and look.
Every number has its character, its own distinctive coloring: 5, for instance, is the gray accountant, the user-friendly solid citizen, the John Major, if you like, of integers; 6 has the springtime bounce of a perky cheerleader, though taken too far, it leads straight to hell (666 is the number of the Beast). And 7 is everybody's lucky number -- we base our lives around 7 seas, 7 heavens and 7 graces (as well, inevitably, as their shadow side, the 7 deadlies). But what of 9? It is, we all know, an odd number (very odd), and an early square. It is a 6 on its head, a circle and a line, the highest digit and the last, with something of the darkness that attaches to last things. Yet it has strange magic in it. Multiply any number by 9, and the sum of the digits will also come to 9 (7X9=63; 6+3=9). Reverse the digits, and the number you get (36) will also be a multiple of 9. Take any number you choose (4,321) and divide it by 9. The remainder you get (1) will be the same as the remainder you get when you add the digits (4+3+2+1) and divide by 9. That is why mathematicians check their calculations by "casting out nines."
Thus 9 is the source of magic squares, pool-table pyramids, and various patterns that reproduce themselves indefinitely. Most of us, however, know it on less formal terms: as a friend to decision making (9 judges on the Supreme Court) and the key to the heavens (9 planets and 9 Muses). Statisticians covet it -- since if all 9 members of a baseball team have 9 at bats (in any number of 9-inning games), their batting averages can be computed instantaneously (2 for 9 is .222, 3 for 9 is .333, 4 for 9 is .444, and so on, through the order). And 9 is a priceless aid to shopkeepers, who will keep on charging $9.99 or $49.95 till the end of time. In binary terms, 9 is 1001 -- the number of adventure and romance; in England you dial 999 for emergencies (to reverse, perhaps, the diabolic effect of 666). Yet 9 also has an edge to it, the menace that comes from lying along a fault line: it is the number just before the boxer is counted out, the cat runs out of lives, the lover slams the door.
Every number, of course, is only what we make of it, and one man's anguished 10-1 is another's rosy 2+3+4. In fact, 4 was the divine tetraktys for Pythagoras, and we comfort ourselves still with 4 seasons, 4 directions and 4 elements. Yet in China there are 5 of each -- not least, perhaps, because the character for 4 is a homonym of the character for death (and even now, in many Far Eastern hotels, a fourth floor is as rare as a 13th).