The equal sign was invented by Welsh mathematician Robert Recorde in 1557. He wrote: “I will settle as I doe often in woorke use, a paire of paralleles, or Gmowe [i.e., twin] lines of one length, thus : , bicause noe 2 thynges, can be more equalle.” His equal signs were about five times as long as the current ones, and it took more than a hundred years for his equal sign to be accepted. Previously Descartes used the symbol for Taurus, turned sideways, as a way to represent equality.
Fingertips: Factoids
