The number of days less in a 400-year period after the adoption of the Gregorian calendar, created by Pope Gregory XIII in 1582 to reform the old Julian calendar.
The minimum number of complete (full) weeks in a month.
The number of months in a quarter of a year.
March’s birthstone is aquamarine, jasper or bloodstone (for wisdom).
March’s flower is violet or jonquil.
March’s full moon is named “Sap Moon”.
The number of U.S. states which do not use Daylight Saving Time: Arizona, Hawaii and Indiana, which has 3 different time zones.
The number of different time zones used by the state of Indiana:
 76 counties using Eastern Time Zone all year, excluding 16 counties bordering other states,
 Six counties near Chicago, Illinois and 5 near Evansville, Indiana use in Central Time Zone together with Daylight Saving Time, and
 Two counties near Cincinnati, Ohio and 3 near Louisville, Kentucky use Eastern Time Zone together with Daylight Saving Time.