The equals sign was invented in 1557 by Welsh mathematician Robert Recorde. He was tired of writing "is equal to" in his equations and chose the two parallel lines because "noe 2 thynges, can be moare equalle." This simple symbol revolutionized written mathematics, making it much more streamlined and easier to follow.
1557年威尔士数学家Robert Recorde 发明了等号。他写累了“相等”， 然后用两根平行线来表示相等。这一简单的符号给书写数学带来了革命。