The question "What does the term “86'd” relate to?" made me wonder what similar cases we have in English. I'd like to know some other numbers that have a commonly understood meaning beyond their use as a mere number.
I have seen "666" used many times with a special meaning. It is written on fences, and used in US movies like "The Exorcism of Emily Rose": I believed that its meaning is commonly known. However, I was bewildered by an answer contending that the meaning of "666" was unknown. Is 666 commonly understood?
(For example, in Russian, the number 7 symbolises luck, if anyone knows any Russian.)