Newly Enlightened, the mark is not money, it more to do with idolatry and the worship of animals or man. 666 which is the symbolism used regarding this mark is taken from Jewish idiomatic language; instances of which are in several earlier places in the bible such as when Nebuchadnezzar built a statue.
Daniel 3:1 King Nebuchadnezzar made an image of gold, sixty cubits high and six cubits wide, and set it up on the plain of Dura in the province of Babylon.
I won’t go into the details but as you can see it has 66 connected to it in terms of cubits, and also later in the chapter 666 is there, but encoded within the lists of the instruments to be played when worship of it was supposed to happen.
Man was created on the sixth day in Genesis, different from the animals but not on the fabled seventh day of rest.
Also note that Goliath the giant also has 666 connected with him in the book of Samuel, and his head is significant in the story as the stone from the catapult kills him. Note also that Nebuchadnezzar’s dream as interpreted by Daniel is destroyed by a stone in the feet. Hands, feet and head ect all had symbolic idiomatic meaning in Jewish culture.
If one puts all this together with an understanding of the Jewish mind, it becomes clear the kind of thing being communicated. 666 is connected to man, idolatry and domination more or less. At the time Revelation was doing the rounds it was almost certainly referring to Rome, not some microchip or money.
