10/Historical Note

Historical Note on $10$ (Ten)

Aristotle made the obvious statement that $10$ is the usual number base because we have $10$ fingers. This view was echoed by the Roman poet Ovid.

It is noted that not all cultures use $10$ -- some use $5$ (based on the number of fingers on a single hand) and some use $20$ (based on the total number of fingers and toes).


The number $10$ was considered holy by the Pythagoreans, who set great score to the fact that $10 = 1 + 2 + 3 + 4$.

They knew about $8$ celestial bodies:

Sun, Moon, Mercury, Venus, Earth, Mars, Jupiter, Saturn

and also believed in the Central Fire.

In order to satisfy their belief that $10$ was such a special number, they hypothesized the existence of a Counter-Earth which orbited the Central Fire in such a position as to be hidden from us by the Sun.


The number $10$ is expressed in Roman numerals as $\mathrm X$.

It has been suggested that this originates from:

joining up two $\mathrm V$s, each representing $2$ hands held up showing the full $5$ fingers

or:

an abbreviation for $10$ tally marks, with a line struck through them to indicate that $10$ had been reached.


Also see

  • Definition:Tetractys


Sources

  • 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $10$
  • 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $50$
  • 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $10$
  • 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $50$
  • 2008: Ian Stewart: Taming the Infinite ... (previous) ... (next): Chapter $2$: The Logic of Shape: Pythagoras
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