Fear of the number 13 seems to be ingrained in modern-day culture:
- Many buildings don't have a 13th floor
- Some airports don't have a gate 13; hospitals sometimes skip room 13
- There can never be more than 3 Friday the 13ths in any given year
- Cheat sheet: If a month starts on a Sunday, it will have a Friday the 13th
Read more about the "unlucky" day here.