It is observed by Huet as a remarkable circumstance, that for
calculation and numerical increase the number 10 is always used, and
that decimal progression is preferred to every other. The cause of this
preference arises from the number of our fingers, upon which men
accustom themselves to reckon from their infancy. First, they count the
units on their fingers, and when the units exceed that number, they have
recourse to another ten. If the number of tens increase, they still
reckon on their fingers; and if they surpass that number, they then
commence a different species of calculation by the same agents; as
thus--reckoning each finger for tens, then for hundreds, thousands, &c.
From this mode of reckoning by the fingers then, we have been led to
prefer the number ten, though it is not so convenient and useful a
number as twelve. Ten can only be divided by two and five, but twelve
can be divided by two, three, four, and six.
The Roman numbers are adduced in proof of the origin of reckoning by the
number ten, viz.--
The units are marked by the letter I, which represent a finger.
The number five is marked by the letter V, which represents the first
and last finger of a hand.
Ten, by an X, which is two V’s joined at their points, and which two V’s
represent the two hands.
Five tens are marked by an L; that is half the letter E, which is the
same as C, the mark for a hundred.
Five hundred is marked by a D, half of the letter Φ, which is the same
as M, the mark for a thousand.
According to this, the calculation of the Roman numbers was from five to
five, that is, from one hand to the other. Ovid makes mention of this
mode, as also of the number ten:--
“Hic numeris magno tunc in honore fuit.
Seu quia tot digiti per quos numerare solemnus,
Seu quia bis quino femina mense parit.
Seu quod ad usque decem numero crescente venitur:
Principium spatiis sumitur inde novis.”
Vitruvius also makes the same remark; he says, “Ex manibus denarius
digitorum numerus.”
We have refined, however, upon the convenience which nature has
furnished us with to assist us in our calculations; for we not only use
our fingers, but likewise various figures, which we place in different
situations, and combine in certain ways, to express our ideas.
* * * * *
Many unlettered nations, as the inhabitants of Guinea, Madagascar, and
of the interior parts of America, know not how to count farther than
ten. The Brasilians, and several others, cannot reckon beyond five; they
multiply that number to express a greater, and in their calculations
they use their fingers and toes. The natives of Peru use decimal
progression; they count from one to ten; by tens to a hundred; and by
hundreds to a thousand. Plutarch says, that decimal progression was not
only used among the Grecians, but also by every uncivilized nation.
* * * * *
~Omniana.~