Fatto generale: 743 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 743 is the number of independent sets of the graph of the 4-dimensional hypercube.
Trivia: 743 is an unremarkable number.
Data storica: January 12th is the day in 475 that Basiliscus becomes Byzantine Emperor, with a coronation ceremony in the Hebdomon palace in Constantinople.