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# What are Napier’s bones?

In the sixteenth century, the Scottish mathematician John Napier (1550–1617), Baron of Merchiston, developed a method of simplifying the processes of multiplication and division, using exponents of 10, which Napier called logarithms (commonly abbreviated as logs). Using this system, multiplication is reduced to addition and division to subtraction. For example, the log of 100 (102) is 2; the log of 1000 (103) is 3; the multiplication of 100 by 1000, 100 ? 1000 = 100,000, can be accomplished by adding their logs: log[(100)(1000)] = log(100) log(1000) = 2 3 = 5 = log(100,000). Napier published his methodology in A Description of the Admirable Table of Logarithms in 1614. In 1617 he published a method of using a device, made up of a series of rods in a frame, marked with the digits 1 through 9, to multiply and divide using the principles of logarithms. This device was commonly called “Napier’s bones” or “Napier’s rods.”

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