Mathematical fact: 4823 is the number of triangles of any size contained in the triangle of side 26 on a triangular grid.
Trivia: 4823 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: March 15th is the day in 1986 that Hotel New World Disaster a 1 star hotel collapses in Singapore's Little India's district killing 33 people.