1622
Slide Rule invented by William Oughtred

William Oughtred (5 March 1574 – 30 June 1660) was an English mathematician born in Eton

After John Napier invented logarithms, and Edmund Gunter created the logarithmic scales (lines, or rules) upon which slide rules are based, it was Oughtred who first used two such scales sliding by one another to perform direct multiplication and division; and he is credited as the inventor of the slide rule in 1622. Oughtred also introduced the "×" symbol for multiplication as well as the abbreviations "sin" and "cos" for the sine and cosine functions.