In 900 Julian years there are = 225 leap days. The Revised Julian leap rule omits seven of nine century leap years, leaving leap days per 900-year cycle. Thus the calendar mean year is 365 +  days, but this is actually a double-cycle that reduces to 365 +  = 365.24 days, or exactly 365 days 5 hours 48 minutes 48 seconds, which is exactly 24 seconds shorter than the Gregorian mean year of 365.2425 days, so in the long term on "average" the Revised Julian calendar pulls ahead of the Gregorian calendar by one day in 3600 years.