Archimedes was a Greek mathematician, inventor and engineer from Syracuse, Sicily in the 3rd century BCE. He made important contributions to mathematics through developing new calculation techniques and applying mathematics to physical problems. Some of his key achievements included using the method of exhaustion to calculate the area of shapes and volumes of solids with curved surfaces, proving that the volume and surface area of a sphere is two-thirds that of its circumscribing cylinder, and discovering Archimedes' principle which states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced. He is considered one of the greatest mathematicians of antiquity.