Unlike other calendar systems that use leap days
or leap months to synchronise the calendar with the solar year, the Islamic calendar is completely detached from astronomical seasons marked by the equinoxes and solstices.
That accomplishes the same thing as the dropping of three leap days every 400 years in the Gregorian calendar.
From 1964 through 1995, Gregorian and Iranian leap days fell only three weeks apart.
14 Karin Henriksen of Norway holds the world record for giving birth to the most children on consecutive leap days
Buckingham Palace has calculated that Queen Victoria reigned for 23,226 days, 16 hours and 23 minutes, taking into account 63 years, 15 leap days
and the precise timings of her accession and death.
However, as it would take an entire year of leap days
to complete these tasks, I shall dedicate my time to simply finishing off the ones I have already started.
Like the Gregorian calendar, the Persian calendar is solar, but the lengths of the months are calculated differently, as are leap days
and leap years.
The Julian Calendar system was used until 1582 when Pope Gregory XIII added that leap days
should not occur in years ending in "00" except if divisible by 400, providing further fine-tuning.
During this first millennium, there were 365,000 days plus 240 leap days
and two extra leap days
for years 400 and 800.
To offset this discrepancy, leap days
are skipped in years ending in "00," unless they are divisible by 400.
That formula gets rid of just enough extra leap days
to keep the calendar in synch with the earth's race around the sun.