Editing Doomsday rule (section)

===28-year cycle===
Regarding the frequency of doomsdays in a Julian 28-year cycle, there are 1 leap year and 3 common years for every weekday, the latter 6, 17 and 23 years after the former (so with intervals of 6, 11, 6, and 5 years; not evenly distributed because after 12 years the day is skipped in the sequence of doomsdays).{{Citation needed|date=January 2008}} The same cycle applies for any given date from March 1 falling on a particular weekday.

For any given date up to February 28 falling on a particular weekday, the 3 common years are 5, 11, and 22 years after the leap year, so with intervals of 5, 6, 11, and 6 years. Thus the cycle is the same, but with the 5-year interval after instead of before the leap year.

Thus, for any date except February 29, the intervals between common years falling on a particular weekday are 6, 11, 11. See e.g. at the bottom of the page [[Common year starting on Monday]] the years in the range 1906–2091.

For February 29 falling on a particular weekday, there is just one in every 28 years, and it is of course a leap year.