Elementary arithmetic, with brief notices of its history... by Robert Potts.

NUMERATION AND NOTATION.
ART. 1. It is probable that the earliest efforts in counting were very
limited, and did not extend beyond the simple wants of primitive
life. As the human race multiplied on the earth and their wants
increased, different methods of numbering would be devised, and improvements made, until necessity, the mother of inventions, led to the
discovery of that perfect system which has superseded all others, and
is now in almost universal use in the civilised world. To count or to
number is nothing more than to form ideas of assemblages of things
considered as units, and to assign names to each of these assemblages.
This is the first process of the human mind in the science of numbers.
Every particular object or thing suggests the idea of unity or one
thing to the mind, and every assemblage of tlings suggests the idea
of numbers composed of a greater or less assemblage of units. If
such a collection of things be considerable, it is impossible to determine at first sight, with exactness, the whole number, and to name
the sum of them. Our senses suggest only the undefined idea of a
multitude. Nature has provided a kind of arithmetical instrument,
more generally used than is commonly imagined, namely, the two
hands, with the five fingers on each hand. It is highly probable that
these were the first instruments used by men to assist them in the art
of numbering. There is a strong presumption in favour of the truth
of this opinion, that all civilised nations from the earliest times have
counted by the number of the fingers on one or on both hands. No
reason can be discovered why the number five or ten should be chosen
rather than any other number for the basis of counting, except the primitive practice of counting by the fingers of one or of both hands. It is,
besides, not improbable that in early times men counted by their
fingers, objects which did not exceed that number. They could also
count the exact number of tens in an assemblage of objects, and note
the units which remained less than teas. But as the fingers could
only serve them to ascertain that remai:nder of units above the tens,
they wanted something to determine the number of tens. Wthen this
number was large, they were led to look for new helps. Nature
presented them with many things equally fit to assist them in this
operation, as pebbles or counters. It is now easy to imagine how
that, by the help of the fingers and little stones, a method of numbering might be devised, and considerable calculations might be
performed.
A heap of pebbles consisting of individual pebbles can be numbered
by arranging them in sets of ten pebbles each, and reserving the
pebbles over, which do not make a complete set of ten.