math_fact: 280 is the number of ways 18 people around a round table can shake hands in a non-crossing way, up to rotation.
trivia: 280 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: October 6th is the day in 1854 that the Great fire of Newcastle and Gateshead starts shortly after midnight, leading to 53 deaths and hundreds injured.