In his inspired Word, God provides the needed clues with regard to the number 666, the name, or mark, of the wild beast of Revelation n chapter 13.In this article, we will look at four main lines of reasoning—vital clues—that will reveal the meaning of the mark of the beast. We will consider (1) how Bible names are sometimes chosen, (2) the identity of the wild beast, (3) what is meant by 666 being “a man’s number,” and (4) the significance of the number 6 and why it is written in triple digits, namely, 600 plus 60 plus 6, or 666.—Revelation 13:18. Reference http://wol.jw.org/en/wol/d/r1/lp-e/2004241?q=666&p=par Compare http://www.bing.com/search?q=666.—Revelation+13:18&form=APPCS1
Because people don't understand Revelation on so many levels. In this case, 666 (in some copies of Revelation the number is 616) is just Gematria for Nero(n) Caesar. (The n in parenthesis is the reason for the fire emcee of 50 alluded to above.) There is no devil, and the devil has no number. Just recall that if you wanted to survive in Nero's Rome, you had to use code when critiquing him.
Also it causes all, both small and great, both rich and poor, both free and slave, to be marked on the right hand or the forehead, so that no one can buy or sell unless he has the mark, that is, the name of the beast or the number of its name. This calls for wisdom: let the one who has understanding calculate the number of the beast, for it is the number of a man, and his number is 666. (Revelation 13:16-18)
A tremendous amount has been written about the Bible's one and only reference to the mysterious number "666." Using various methods of equating numbers with letters of words or names, a wide variety of interpretations have been made. A few are reasonable guesses (e.g. Nero Caesar, Romulus, Lateinos, Vicarius Filii Dei), while numerous others are extremely unlikely.
Although it's not entirely clear, yet, what the "666" itself means, the Bible does provide many Scriptures relating to the "beast" that the number represents:
A "new" world economic and military superpower that will represent the final prophesied revival of the ancient "Holy Roman Empire" (Daniel 2:31-45, Revelation 13:1-3, 17:9-14) (see Daniel's Statue and Birth Of A Superpower), which has actually existed in Europe for many centuries. A Satan-possessed human who will eventually become its absolute ruler, while claiming divine status (Revelation 13:4-6). The "beast" is a term used to describe both this human, and the great political/religious superpower that he will lead (see Emperor and The Antichrist). A great religious leader who will support the beast. He will perform spectacular Satan-powered "miracles" that will deceive a majority of the citizens of every nation on earth into obeying and actually worshiping the "beast." (Revelation 13:4, 7-8, 12-14) (see Emperors and Popes). Because of this worldwide deception, undeceived Christians in even the most strongly-defended countries will not escape persecution because, in most cases, it will not come from foreign invaders, but from fanatically-deceived "Christians" of their own nation. The deceived masses will think that they serving God while they are actually martyring His people (e.g. John 16:2-3, Revelation 13:7). The right and ability to buy, sell and work (Revelation 13:17). The personal acceptance or refusal of the "mark" of the beast (Revelation 13:16). The time will come when there will be no doubt about who and what the "666" symbol is all about. Why? Because the end-time account of the true church is about choices that every genuine Christian then living will have to make, and the consequences of those choices.
God's people can choose to obey Him and reject the mark of the beast, but then be persecuted by the beast and deceived humans (Revelation 13:7,10,15 and 17:6), or accept the mark of the beast and face the wrath of God that will come upon those who do so (Revelation 16:2). It will be a deliberate, knowing choice, and at that time there will be no doubt what it means.