math_fact: 2704 is the number of necklaces with 9 white and 9 black beads.
trivia: 2704 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: May 27th is the day in 1968 that the meeting of the Union Nationale des Étudiants de France (National Union of the Students of France) takes place.