This is the board of José Figueroa-O’Farrill at the University of Edinburgh, who is working on a project related to ‘temple mathematics’ with his Year 4 undergraduate project group. In 17th century Japan, tablets inscribed with mathematical problems would be hung in temples as gifts to the gods. The problem being discussed on this board is a plane geometry problem which appeared first in a tablet dating from 1823 in Yamagata prefecture (northern Japan). It asks to find the radius of the middle circle in terms of the radii of the two smaller circles at either side. The students will be putting these sorts of problems on posters around the maths department in Edinburgh – you can follow their efforts on their lovely website.