Fait mathématique: 1756 is the number of ways to stack 28 boxes in a line so that each box lies on the table or on a box next to 2 boxes.
Culture générale: 1756 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: October 21st is the day in 1931 that the Sakurakai, a secret society in the Imperial Japanese Army, launches an abortive coup d'état attempt.