William Oughtred invents the slide rule
William Oughtred (5 March 1574 – 30 June 1660) was an English mathematician born in Eton.
A slide rule is a mechanical computing device, or analogue computer, that makes complicated calculations much simpler. Slide rules facilitate calculations such as multiplication, division, exponents, roots, logarithms, and trigonometry.
After John Napier invented logarithms, and Edmund Gunter created the logarithmic scales (lines, or rules) upon which slide rules are based, it was William Oughtred who first used two such scales sliding by one another to perform direct multiplication and division. He is credited as the inventor of the slide rule in 1622.
William Oughtred also introduced the "×" symbol for multiplication as well as the abbreviations "sin" and "cos" for the sine and cosine functions. Before the invention of the desktop calculator and electronic computers in the mid-20th Century, the slide rule was a very common calculation aid, used by people such as students, engineers, and scientists.