Hecho matemático: 878 is the number of 3×3 sliding puzzle positions that require exactly 29 moves to solve starting with the hole on a side.
Trivia: 878 is an uninteresting number.
Fecha histórica: May 27th is the day in 1971 that the Dahlerau train disaster, the worst railway accident in West Germany, kills 46 people and injures 25 near Wuppertal.