A local, sandwich shop charges $6.66 for a specific sub after tax if you don't get the full meal. Owner or corporate office probably never thought about it. The locals regularly change the amount, often subtracting, because so many people don't want to pay that specific number. I always try to do some dark, comedy routine the second I see it if it's a new employee in case they're superstitious. At least one looked like the apocalypse was happening before I said, "Nah, I'm just messing with you." The coworkers always get a laugh out of those.

Outside that, I've heard mark of the beast from so many people about so many things over the decades that I'm sure it factors into a lot of political decisions where popular vote counts. The wording is kind of catch-all given mark is so ambiguous, it mentions a name, and it has a number. A person can project it on anything.