DaysPlus[{year, month, day}, n] gives the date n days after the date {year, month, day}.DaysPlus[{year, month, day, hour, minute, second}, n] gives the date n days after the ...

EasterSundayGreekOrthodox[year] gives the date of Easter Sunday according to the Greek Orthodox Church using the Gregorian system.

EasterSunday[year] gives the date of Easter Sunday in the Gregorian calendar system.

Friday is a day of the week.

Gregorian represents the Gregorian calendar system.

Islamic represents the Islamic calendar system.

Jewish represents the Jewish calendar system.

JewishNewYear[year] gives the date of the Jewish New Year occurring in Gregorian years between 1900 and 2099.

Julian represents the Julian calendar system.

Monday is a day of the week.