1. Gottfried Wilhelm von Leibniz

2. Leibniz constructed the first mechanical calculator, known as the Stepped Reckoner, capable of multiplication and division. He also developed the modern form of the binary numeral system, used in digital computers. The Leibniz calculator incorporated a new mechanical feature, the stepped drum — a cylinder bearing nine teeth of different lengths which increase in equal amounts around the drum. Although the Leibniz calculator was not developed for commercial production, the stepped drum principle survived for 300 years and was used in many later calculating systems.

4. Main contribution: CALCULUS! Two other main ideas: Universal language – a language which all knowledge could be formally expressed Calculus of Reason – reduce all problems to numerical computation Other things he contributed to: multiple indices to state the result of three linear equations study of differential equations discovering the method of separation of variables reduction of homogeneous equations to separable ones the procedure for solving first order linear equations laid the foundations of the theory of determinants integrated rational fractions in trigonometric and logarithmic functions produced a theory of special curves one of the first to work out the properties of the binary number system