The calendars of two leap years with a gap of 28 years will be the same. E.g. the calendars of 1908 and 1936 are exactly the same. The calendars of two leap years with a gap of 12 years will be the same if a century year, which is not a leap year, falls between the two years. E.g.since 1900 falls between 1896 and 1908, the calendars of 1896 and 1908 are exactly the same. Also, we can see that the calendars of 1896 and 1936 (a gap of 40 (12 + 28) years) are exactly the same.