math_fact: 7788 is the index of a triangular number containing only 3 different digits.
trivia: 7788 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: April 27th is the day in 1992 that Betty Boothroyd becomes the first woman to be elected Speaker of the British House of Commons in its 700-year history.