Solving formulas, determining vectors, learning the basics of multiplication—these are all part of learning math. And for some, this is torture. But what if these tasks were done on a smartphone, solved in a team—and performed outdoors? The MathCityMap (MCM) app sends students on mathematical scavenger hunts in their towns. For children and teenagers, this means getting out of the classroom, finding their way through town via app, solving tasks at different locations, receiving direct feedback and, if necessary, using digital aids to do so. This makes arithmetic fun and relevant to real life. The developer side of the app permits users to create their own tasks for the MCM portal and its European community.