I know this has probably already been posted regarding 666 building but I have little time to contribute today and want to do my part.
"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.
18 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."
Read Revelations 13. I suggest the New American Standard version or English Standard Version. They are both word for word translation and easy to understand. NIV is a thought for thought translation and sometimes loses words. If you go to bible.hub or biblegateway, you can choose different translations.