He Invented the Equals Sign — Then Died in a Debtors' Prison
In short: Robert Recorde gave mathematics one of its most useful symbols — the equals sign. Yet the Welsh physician and mathematician died in 1558 in a debtors' prison, after a dispute over mint funds and a lawsuit left him unable to pay. The symbol that now appears in every classroom outlived the man who could not buy his freedom. Why did algebra need a new symbol? Before Recorde, equations were mostly written out in words. That made even simple algebra slow to read and easy to misread. In his 1557 book The Whetstone of Witte , Recorde proposed two short parallel lines to stand for equality. His reason, in modern terms, was simple: no two things can be more equal than a pair of parallel lines of the same length. The idea was so clear that it stuck — and it is still with us today. Who was Robert Recorde? Recorde was a Welsh scholar who studied at Oxford and Cambridge and worked as a physician. He also wrote books that brought mathematics and astronomy to English readers at a time ...