Fatto matematico: 4930 is 6677_{9} = 2A2A_{12} = 2323_{13} = 1010_{17}, each using two digits exactly twice each.
Trivia: 4930 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: June 30th is the day in 1936 that Emperor Haile Selassie of Abyssinia appeals for aid to the League of Nations against Italy's invasion of his country.