Denis Guedj was a French novelist and a professor of the History of Science at Paris VIII University. He spent many years devising courses and games to teach adults and children math. *-- Wikipedia* *Photo Attribution:* Photographe de la Ville de Saint-Dié-des-Vosges, dans le cadre de sa mission ; scan par Ji-Elle, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons