Fait mathématique: 7880 is the maximum value of n so that there exist 4 denominations of stamps so that every postage from 1 to n can be paid for with at most 26 stamps.
Culture générale: 7880 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: July 28th is the day in 1896 that the city of Miami, Florida is incorporated.