54
GREEK NUMERICAL NOTATION
It is believed to date from the second century a. d., and it
probably came from Alexandria or the vicinity. But the
form of the characters and the mingling of capitals and small
letters both allow of an earlier date; e. g. there is in the
Museum a Greek papyrus assigned to the third century B.c.
in which the numerals are very similar to those on the tablet. 1
The second requirement is connected with the fact that the
Greeks began their multiplications by taking the product of
the highest constituents first, i.e. they proceeded as we should
if we were to begin our long multiplications from the left
instead of the right. The only difficulty would be to settle
the denomination of the products of two high powers of ten.
With such numbers as the Greeks usually had to multiply
there would be no trouble; but if, say, the factors were un
usually large numbers, e.g. millions multiplied by millions or
billions, care would be required, and even some rule for
settling the denomination, or determining the particular
power or powers of 10 which the product would contain.
This exceptional necessity was dealt with in the two special
treatises, by Archimedes and Apollonius respectively, already
mentioned. The former, the Sand-reckoner, proves that, if
there be a series of numbers, 1, 10, 10 2 , 10 3 ... 10 m ... 10»,.,,
then, if 10 m , 10» be any two terms of the series, their product
10 m . 10» will be a term in the same series and will be as many
terms distant from 10» as the term 10 m is distant from 1;
also it will be distant from 1 by a number of terms less by
one than the sum of the numbers of terms by which 10 m and
10» respectively are distant from 1. This is easily seen to be
equivalent to the fact that, 10 m being the (m+l}th term
beginning with 1, and 10» the (n + l)th term beginning
with 1, the product of the two terms is the (m + n +1 )th
term beginning with 1, and is io m+ ».
(hi) Apollonius’s continued multiplications.
The system of Apollonius deserves a short description. 2 Its
object is to give a handy method of finding the continued
product of any number of factors, each of which is represented
by a single letter in the Greek numeral notation. It does not
1 David Eugene Smith in Bibliotheca Mathematica, ix 3 , pp. 193-5.
2 Our authority here is the Synagoge of Pappus, Book ii, pp. 2-28, Hultsch.