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Representing Equality

Writing the left-hand side of an equation above the right-hand side was how equality was indicated by the Hindus (seventh century). The Greeks used their phrase for, "is equal to," between left and right sides of equations to demonstrate equality.

Robert Recorde, an English textbook writer, physician, and math teacher, gave us the modern equality symbol (=) in his The Whetstone of Witte in 1557. His justification for using a pair of equal parallel line segments for this symbol, "bicause noe 2 thynges can be moare equalle."

Below is a list of some of the things used to represent equality along with the date and person who used it.

DatePersonEquality Symbol
1494Pacioli facia
1514Hoeckedit is ghelijc
1521Ghaligai
1525Rudolff aequatus
1545Cardanaequalis
1553Stifelaequata
1557Recorde====
1559Buteo[
1572BombelliEqualeà
1585Stevinegalesà
1591Viète aequatur
1631Harriot====
1693Wallis=
(Historical Topics for the Mathematics Classroom, 1969, p. 262-263.)