Napier’s bones

mathematics

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July 1, 2026

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Napier's bones were a calculating tool invented by Scottish mathematician John Napier in the early 17th century. This device, consisting of graduated rods, was designed to simplify the processes of multiplication and division. The invention was based on the principles of logarithms, which Napier also conceptualized.123

Logarithms work by converting multiplication and division problems into simpler addition and subtraction problems, significantly speeding up calculations. Napier's bones provided a physical method for performing these logarithmic calculations, making them accessible for practical use in fields like astronomy and navigation. This invention was a precursor to the slide rule.32

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John Napier
Contribution to mathematics
…of small rods known as Napier’s bones, a device that was the forerunner of the slide rule. He made important contributions to spherical trigonometry, particularly by reducing the number of equations used to express trigonometrical relationships from 10 to 2 general statements. He is also credited with certain other spherical…
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…of small rods known as Napier’s bones, a device that was the forerunner of the slide rule. He made important contributions to spherical trigonometry, particularly by reducing the number of equations used to express trigonometrical relationships from 10 to 2 general statements. He is also credited with certain other spherical…
Read More