timeline By zeynepncan Period: 1 CE to 1 CE Math timeline 200 Beginning of Math 325 Euclid of Alexandria 500 Pythagoras 1072 Cubic Equations 1484 Earliest French Algebra Book 1489 Use of + and - 1557 Equals Sign invented 1591 Variables 1617 Napier Rods 1620 Slide Rule 1642 The Calculator 1706 The symbol TT 1888 American Mathematical Society 1912 The Turing Machine 1923 Piaget 1948 Educational Testing Service Charted - Beginning of SAT 1957 Sputnik launched 1991 Smart board introduced 2002 No Child Left Behind signed into law