UREM-ULB :
Unité de Recherche sur l’Enseignement des Mathématiques

Each day offers a different theorem (or lemma, law, formula or identity), each one worthy of adorning the walls of a mathematical Alte Pinakothek, Guggenheim, Louvre, Nail Factory, Tate, Uffizi or Zach Feuer.

Each theorem has been presented so as to be appreciated by as wide an audience as possible. If you can have a go at a Sudoku puzzle (certainly a mathematical creature even though not an arithmetical one) then you can have a go at today’s theorem.