Fatto generale: 400 is the number of years in a period of the Gregorian calendar, of which 97 are leap years and 303 are common.
Fatto matematico: 400 is a boring number.
Trivia: 400 is the number of years in a period of the Gregorian calendar, of which 97 are leap years and 303 are common.
Data storica: February 3rd is the day in 1870 that the Fifteenth Amendment to the United States Constitution is ratified, guaranteeing voting rights to citizens regardless of race.