general_fact: 720 is the number of degrees in two circles (= 2 × 360).
math_fact: 720 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 720 is five gross (= 500 duodecimal, 5 × 144).
historical_date: December 20th is the day in 1991 that a Missouri court sentences the Palestinian militant Zein Isa and his wife Maria to death for the honor killing of their daughter Palestina.