Hecho general: 678 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 678 is a member of the Fibonacci-type sequence starting with 1 and 7.
Trivia: 678 is a boring number.
Fecha histórica: November 8th is the day in 1965 that the British Indian Ocean Territory is created, consisting of Chagos Archipelago, Aldabra, Farquhar and Des Roches islands.