Ten

By David Simmons

There has been little on television over the past week but features related to the 10th anniversary of the terrorist attacks of September 11, 2001. And of course the question on top of everyone's mind is: What is the significance of 10 years?

The answer, of course, is "absolutely nothing". We mark things by tens because we have 10 fingers, a fact that has nothing at all to do with a gang of wackos flying airliners into buildings.

The September 2001 attacks are often described as "world-changing", but in fact that description is far more apt to an unrecorded event: the day humankind learned to count past the number 10 (or 20, assuming this happened before the invention of the full-coverage shoe). However, even with that giant achievement, humans were unable to leave behind their 10-digit-based mathematical origins. Despite built-in flaws and even clashes with the cosmos itself, we cling to our base-10 numbering system.

Our own planetary system tells us that 12 would be a better base, as there are 12, not 10 lunar phases. The decimal-fraction system shows how this is so. One of the most useful fractions we have, one-third, cannot be conveniently expressed decimally: it becomes 0.333... with infinite repetition. One-fourth is not much better; it requires two numerals to designate as a decimal. But with a base-12 system, one-half would be 0.6, one-third would be 0.4 and one-fourth would be 0.3, vastly simplifying calculations at all levels. We actually do use base-12 for time, as you can see by looking at a (non-digital) clock: 12 hours, each divided into 60 minutes, for a total of 3,600 seconds – all numbers easily divisible by the prime numbers 2, 3 and 5.

This timing anomaly may derive from that most basic of clocks, the lunar cycle. Yet even here we see reflections of our obsession with the number of fingers we possess, for the 12th month is called "December", which means "10th month". This actually happened not because there were once 10 months in the year but because the pre-Julian calendar started in March, not January. Still, one would have thought that the various renamings of the months that took place over the centuries would have dealt with this oddity had we not been so decimally biased.