Hecho matemático: 340 is a value of n for which n!.
Trivia: 340 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fecha histórica: December 5th is the day in 1958 that Subscriber Trunk Dialling (STD) is inaugurated in the UK by Queen Elizabeth II when she speaks to the Lord Provost in a call from Bristol to Edinburgh.