Hecho general: 50 is the gold or "golden" wedding anniversary in years of marriage.
Hecho matemático: 50 is the smallest number that can be written as the sum of of 2 squares in 2 ways.
Trivia: 50 is the speed limit, in kilometers per hour, of Australian roads with unspecified limits.
Fecha histórica: February 19th is the day in 197 that Emperor Septimius Severus defeats usurper Clodius Albinus in the Battle of Lugdunum, the bloodiest battle between Roman armies.