Fatto generale: 520 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 520 is the number of ways to place 2 non-attacking kings on a 6×6 chessboard.
Trivia: 520 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: June 3rd is the day in 1665 that James Stuart, Duke of York (later to become King James II of England) defeats the Dutch fleet off the coast of Lowestoft.