BONES calculator JOHN NAPIER’S Need To Know


Have you ever wondered how the Romans did multiplication? Even the two-times table expands into
nightmarish proportions if you try to work it out in Latin numerals. Hardly surprising, then, that when HinduArabic
numbers were imported into Europe at the beginning of the 13th century, merchants and mathematicians enthusiastically adopted the new system of nine digits plus zero that we still use.
Even so, when dealing with large numbers, it was easy to make mistakes. Division posed still more of a
problem, to say nothing of square roots. Four centuries later, the Laird of Merchistoun – better known as
Scottish mathematician John Napier (1550– 1617) – decided it was time to make routine arithmetical tasks easier.
He invented a special type of abacus, a set of rotating rods each inscribed many times over with the ten basic
digits. Soon known as Napier’s bones (expensive ones were made of bone or ivory), this device made it possible
to carry out long calculations quickly and accurately. You just line up the rods and read off the answer


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