
The 36 officers problem
Euler may not have cracked this problem completely, but it led to a lot of important work, including on what we today know as sudoku.
Can you find a path through on this city map that crosses every bridge exactly once? Euler's answer to this problem started off the filed of graph theory.
Mathematicians mingle at the ECM at the Technische Universität Berlin. Image from the ECM website.
Prime numbers, fluid dynamics and architecture at the European Congress of Mathematics in Berlin.