Fatto generale: 724 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 724 is the number of different arrangements of 10 non-attacking queens on an 10×10 chessboard.
Trivia: 724 is an unremarkable number.
Data storica: December 24th is the day in 2008 that Lord's Resistance Army, a Ugandan rebel group, begins a series of attacks on Democratic Republic of the Congo, massacring more than 400.