In mathematics, the order of operations, believed to have been in its formative stages in the 16th century, is not credited to a single inventor. This mathematical convention developed as a conceptual process in solving mathematical equations involving multiple operators.
Some of the earlier works that contributed to the modern rules of the order of operations included "Mental Arithmetic" by M.A. Bailey, "Text-Book of Algebra" by G.E. Fisher, "High School Algebra, Elementary Course" by Slaught and Lennes, and "First Course of Algebra" by Hawkes, Luby and Touton. One common memory device for remembering the order of operations is "PEMDAS," which is an acronym for Parenthesis, Exponents, Multiplication and Division, and Addition and Subtraction. Solving a mathematical equation is done from left to right. Multiplication and division are equal in rank, as well as addition and subtraction.