Known as the Father of Mathematics, Archimedes was the most important mathematician and inventor in ancient Greece. Many of the inventions he created as solutions to problems presented to him by King Hiero II are still in use today. Accomplished in both theoretical and practical mathematics, Archimedes is best known for mechanical inventions like Archimedes' screw, the Claw of Archimedes, and the heat ray as a weapon, as well as his discoveries using water displacement and buoyancy. But his contributions to pure mathematics, such as his approximation of pi, laid the groundwork for modern calculus.