There is actually a pattern to work out when a calendar will repeat itself.
Generally, a calendar repeats itself every 11 years.
However, the exception is the year following a leap year, which will only be repeated 6 years later.
This is due to the fact that the amount of days in a regular calendar is a always worked out by multiplying the number of days in a week (7) with a remainder of 1.
Did you know this means non-leap years always start and end on the same day of the week?
Also, the same date next year - in non-leap years - is always one day later.
So March 23rd in 2014 is a Sunday, in 2015 March 23rd will be a Monday.