More information to add to the "teachers are idiots" file...
The origin of 666 greatly predates Hollywood, by about two thousand years.
The book of Revelations, chapter 13, verses 17-18: And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name. Here is wisdom. Let him that hath understanding count the number of the beast: for it is the number of a man; and his number is Six hundred threescore and six.
A score is 20. Pick whichever translation you want, that one in particular is from King James. There is argument as to whether 666 is a transcription error, but 696 is pulled from someone's ass recently, probably your teacher's. It would hardly be the first time some numbnut with a general education degree made something up.
There are two very old writings that have it as 616, they may have been right, and they may have been fudged to poke fun at the asshole in chief of the time, no one liked Nero much, his name added up to 616.