Aarav was born on 29 February 2004. Counting only the days on which the date 29 February really appears in the calendar, how many birthdays on his true date will he have had by the end of 2028?

The date 29 February appears only in leap years, that is in years divisible by 4 (none of the years here ends in 00, so the century rule never bites). The leap years after his birth and up to 2028 are 2008, 2012, 2016, 2020, 2024 and 2028 — six of them. The traps: 7 counts the day he was born as a birthday as well, but that day was his birth, not the return of the date; 5 stops at 2024, forgetting that 2028 is itself divisible by 4; 24 counts one for every year from 2005 to 2028, which is what an ordinary birth date would give.