general_fact: 471 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 471 is the smallest number with the property that its first 4 multiples contain the digit 4.
trivia: 471 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: April 15th is the day in 1632 that Battle of Rain; Swedes under Gustavus Adolphus defeat the Holy Roman Empire during the Thirty Years' War.