Have you ever wondered why we use only ten digits and the decimal system and not something else? The number twelve once was a big contender. Look at the number of eggs in a dozen, the hours on a clock, months in a year and even the number of courses in a year.
Mathematically 12 is easier to work with than 10. 12 is divisible by 2, 3, 4 and 6 compared to just 2 and 5 for the number 10. Fractions like one-third (0.33333) and one-quarter (0.25) are awkward in the decimal world, while one-third and one-quarter would be exact numbers (0.4) and (0.3) in the duodecimal world. The number twelve embraces divisibility while ten resists it.
This small difference once mattered greatly. In trade being able to split goods into halves, thirds and quarters was not just convenient, it was more efficient. The duodecimal system was not a theoretical curiosity but a working tool.
4000 years ago, the Sumerians used a base-60 system. When counting on their hands they counted the number of sections per finger. One hand has twelve sections. With two hands you can then count to twenty-four, that is the reason that the day is split into two halves of twelve hours.
So, if twelve was more efficient and used before base-10, why did ten take over? The answer is simple: biology. We count with what we have, and we have ten fingers. Counting in tens requires no technique and comes natural to humans. As cultures mingled the 10-based system spread faster and was easier to use. But with standardization came loss. The metric world is easy to teach and scale, yet less flexible in the everyday arithmetic.
Despite the dominance of the 10-based system, twelve refused to disappear and survives where it still makes sense. Time, geometry and trade. The day divides into twelve hours twice. The circle is divided into twelve groups of thirty degrees. We still talk about “a dozen” as a natural unit of measure.
But next to the decimal and duodecimal system there are also other systems used. Computers use binary, and engineers use a base-16 system. Once again humans have chosen a numerical system that fit the task, not the fingers.
Our number system may feel absolute, but it is a choice of the way we want to perceive the world. The orbit of planets, growth of trees and the speed at which light travels all follow ratios. Nature doesn’t care about bases. Whether we divide the day into ten hours or twelve, the sun will still rise and set. Our choice of numbers describe reality but do not define it.
Base-10 triumphed because it was fast and easy to use, not because it was truer. Base-12 lingered because it worked, not because it was simple. In that tension between simplicity and suitability lies a timely lesson. What suits the hand does not always fit the world.
Imagine for a moment that we had twelve fingers instead of ten. Our timetables would look much neater, calculations of fractions would have been easier. Metrics might flow in twelves, currencies might flow in twelves. Nothing in mathematics would truly change. Only our perception of it.
Mathematics begins with human choice, the base we count in, the symbols we use. This choice all comes back to convenience and convention. Civilizations choose what works, and sometimes forget what worked better. The world may move in tens, but the number twelve has certainly left its mark.