Mamikon A. Mnatsakanian (Armenian: Մամիկոն Մնացականյան) is Project Associate at Project Mathematics! at the California Institute of Technology. He received a Ph.D. in physics in 1969 from Yerevan State University, where he became professor of astrophysics. As an undergraduate he specialized in the development of geometric methods for solving calculus problems by a visual approach that makes no use of formulas, which he later developed into his system of visual calculus. In 1959 he discovered a new proof of the Pythagorean theorem.