With a flourishing agricultural economy , ancient Babylon , located in modern - day Iraq , was one of the first societies complex enough to need modern record keeping . The ancient Babylonians were therefore among the first to develop a sophisticated counting system.
They developed positional numbering the system whereby not only a symbol but also its position relative to others symbols expresses value. Positional numbering allowed large quantities to be expressed with simple symbols pressed into clay tablets.The Babylonian sexagesimal , or base 60 , system grouped number by set of 60 --60^2, 60^3 and so on just as modern counting uses the symbol I for set of 10: 10^2 (100) , 10^3 ( 1,100) .
Clay tablets have come down through history that clearly show the Babylonians advanced understanding of numbers . The tablet known as Plimpton 322 shows a sequence of numbers that appear to express the equation " x^2 + y^2= z^2." In other words , the Babylonians had a version of what would later be called the Pythagorean theorem.