Probability theory
The Cartesian Coordinate System was discovered by René Descartes in 1637 (and independently by Pierre de Fermat at the same period). The first calculator by Blaise Pascal (Pascaline) was made in 1642. (see also Adding machine) Probability theory was developed by Pierre de Fermat and Blaise Pascal in the seventeenth century (with Gerolamo Cardano and Christiaan Huygens).