Räknestickor

Räknestickor, often translated as slide rules, were mechanical analog computing devices used primarily for multiplication and division, and more complex operations like powers, roots, logarithms, and trigonometric functions. They were invented in the early 17th century by William Oughtred in England, based on the concept of logarithms developed by John Napier.

The basic principle of a räknesticka relies on the property of logarithms that the sum of logarithms is the logarithm of the product. A räknesticka consists of at least two movable scales, usually logarithmic, that slide against each other. By aligning specific marks on these scales, users could perform calculations by adding or subtracting lengths on the logarithmic scales, which corresponded to multiplying or dividing the numbers marked on the scales.

Räknestickor were widely used by engineers, scientists, and students from the 17th century until the advent of electronic calculators in the late 20th century. They were an indispensable tool for performing complex calculations quickly before the widespread availability of digital computing. Different types of räknestickor existed with varying complexities and specialized scales for specific fields, such as electrical engineering or navigation. Despite their obsolescence due to electronic calculators, räknestickor remain historically significant as a crucial step in the development of computation.