Definition of equals sign

The equals sign (=) is a mathematical symbol that indicates equality between two quantities. It is commonly used in algebra, arithmetic, and other branches of mathematics. The origin of the equals sign can be traced back to the 16th century, when it was first introduced by the Welsh mathematician Robert Recorde. In his 1557 book "The Whetstone of Wit," Recorde explained the meaning of the equals sign, which he named "two pyes glued togither end to end." He wrote, "I will set as bold a sign of aliностьe, and of equality, as ever my inventione can devise. Two pyes (I say) glued togither back to back, are the markes and distinct signs of due aliinity and equality." The idea behind Recorde's two-legged symbol was to emphasize the idea of equality, as two legs joined together could not be separated without breaking them. The equals sign quickly gained popularity and was adopted by other mathematicians of the time, including the English mathematician and theologian John Napier, who used it in his book "Rabdologiae" (1617). Today, the equals sign is an essential part of mathematical notation, and its use is widespread in various fields, from finance and economics to engineering and computer science. Its concise and universally recognized meaning makes it an efficient and effective tool for communicating mathematical ideas.