The observed and calculated versions of the Islamic calendar do not have regular leap days, even though both have lunar months containing 29 or 30 days each in no apparent order.
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All later writers, including Macrobius about 430, Bede in 725, and other medieval computists (calculators of Easter), continued to state that the bissextum (bissextile day) occurred before the last five days of February.
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In Gilbert and Sullivan's 1879 comic opera The Pirates of Penzance, Frederic the pirate apprentice discovers that he is bound to serve the pirates until his 21st birthday rather than until his 21st year.
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However, the tabular Islamic calendar used by Islamic astronomers during the Middle Ages and still used by some Muslims does have a regular leap day added to the last month of the lunar year in 11 years of a 30-year cycle.
New Year's Day | New Year's Eve | New Year | Chinese New Year | Quantum Leap | One Year Later | Quantum Leap (TV series) | NASCAR Rookie of the Year | High School Musical 3: Senior Year | Four Year Strong | Song of the Year | Grammy Award for Song of the Year | Lunar New Year | International Geophysical Year | Latin Grammy Award for Album of the Year | Helms Foundation College Basketball Player of the Year | Grammy Award for Record of the Year | A Good Year | Wisden Cricketers of the Year | Grammy Award for Album of the Year | year | My Favorite Year | Lo Nuestro Award for Tropical New Artist of the Year | Horse of the Year Show | Hijri year | Fiscal year | Year 2000 problem | NBA Rookie of the Year Award | Japanese New Year | Homicide: A Year on the Killing Streets |
Claddagh rings have been used often as plot devices in films and television, such as in the Buffy the Vampire Slayer episodes "Surprise", "Innocence", "Becoming, Part One", "Leap Year" and "Faith, Hope & Trick".
This formulation may be used in software such as Microsoft Excel to refer to the last day of February as a way of allowing for the fact that its length varies in leap years.
(For example, the chain might become "Leap Yeardrum Major Tommy Thompson Twin Cities," by combining "Leap Year," "Ear Drum," "Drum Major," "Major Tom," "Tommy Thompson," "Thompson Twins," and "twin cities.")
One of the earliest fencepost errors involved time, where the Julian calendar originally calculated leap years incorrectly, due to counting inclusively rather than exclusively, yielding a leap year every three years rather than every four.