The press hails him as a “math guru,” his publisher calls him “Germany’s smartest math professor,” and his subject has been called “8,000 percent cool.” Günter M. Ziegler has made a major contribution to the more positive image math now enjoys among the public. Amid all this, he still makes sure to have time for actual calculations, as he shows in his activities, including as the head of the 25-person Discrete Geometry Working Group, which he brought with him from Technische Universität Berlin to the Dahlem campus of Freie Universität.