Was that someone thinking of the Roman or Julian calendar? February 24 occurs every year in the Gregorian calendar, so far as I know. --MichaelTinkler
No, in both the Roman, the Julian and the Gregorian calendar, February 24 is the added day. Of course February 24 exists in non-leap years also, but it is a different day. The day called "Feb. 24" in non-leap years is actually "Feb. 25" in leap years, and the non-leap year "Feb 28" is leap year "Feb 29". The origins go back to the Roman period -- Feb 24 is the bissextile day -- I think leap year explains it. -- SJK