February 29th
February 29th indicates Leap Year. It occurs once every four years.
4 years 4 yearsThe Summer Olympics are held once every 4 years.
The F.I.F.A world cup is held every four years.
Every four years.
The Olympics are held once every fourth year.
Something that happens every 100 years is called a centennial. It marks a significant milestone or anniversary reaching the 100-year mark.
The letter M.
Yes.
Once every four years.
Some things that happen once every four years include: - Leap Years - US Elections - The Olympics
Biannual
The letter "M"