Revelation 13:11-18

Then I saw another beast rising up out of the earth; he had two horns like a lamb and he spoke like a dragon. He exercises all the authority of the first beast in his presence [when the two are together]. And he makes the earth and those who inhabit it worship the first beast, whose deadly wound was healed. He performs great signs (awe-inspiring acts), even making fire fall from the sky to the earth, right before peoples’ eyes. And he deceives those [unconverted ones] who inhabit the earth [into believing him] because of the signs which he is given [by Satan] to perform in the presence of the [first] beast, telling those who inhabit the earth to make an image to the beast who was wounded [fatally] by the sword and has come back to life. And he is given power to give breath to the image of the beast, so that the image of the beast will even [appear to] speak, and cause those who do not bow down and worship the image of the beast to be put to death. Also he compels all, the small and the great, and the rich and the poor, and the free men and the slaves, to be given a mark on their right hand or on their forehead [signifying allegiance to the beast], and that no one will be able to buy or sell, except the one who has the mark, either the name of the beast or the number of his name. Here is wisdom. Let the person who has enough insight calculate the number of the beast, for it is the [imperfect] number of a man; and his number is six hundred and sixty-six.