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To express the units, they made use of so many vertical "nails"
placed one after, or above, each other, thus [symbols] etc.; tens were
represented by bent brackets [symbols], up to 60; beyond this figure
they had the choice of two methods of notation: they could express the
further tens by the continuous additions of brackets thus, [symbols]
or they could represent 50 by a vertical "nail," and add for every
additional ten a bracket to the right of it, thus: [symbols]. The
notation of a hundred was represented by the vertical "nail" with
a horizontal stroke to the right thus [symbols], and the number of
hundreds by the symbols placed before this sign, thus [symbols], etc.:
a thousand was written [symbols] i.e. ten times one hundred, and the
series of thousands by the combination of different notations which
served to express units, tens, and hundreds. They subdivided the unit,
moreover, into sixty equal parts, and each of these parts into sixty
further equal subdivisions, and this system of fractions was used in all
kinds of quantitive measurements. The fathom, the foot and its square,
talents and bushels, the complete system of Chaldaean weights and
measures, were based on the intimate alliance and parallel use of
the decimal and duodecimal systems of notation. The sixtieth was more
frequently employed than the hundredth when large quantities were in
question: it was called a "soss," and ten sosses were equal to a "ner,"
while sixty ners were equivalent to a "sar;" the series, sosses,
ners, and sars, being employed in all estimations of values. Years and
measures of length were reckoned in sosses, while talents and bushels
were measured in sosses and sars. The fact that these subdivisions were
all divisible by 10 or 12, rendered calculations by means of them easy
to the merchant and workmen as well as to the mathematical expert. The
glimpses that we have been able to obtain up to the present of Chaldaean
scientific methods indicate that they were on a low level, but they
were sufficiently advanced to furnish practical rules for application in
everyday affairs: helps to memory of different kinds, lists of figures
with their names phonetically rendered in Sumerian and Semitic speech,
tables of squares and cubes, and rudimentary formulas and figures for
land-surveying, furnished sufficient instructions to enable any one
to make complicated calculations in a ready manner, and to work out