Revelation 13:13-18

He did astounding miracles, even making fire flash down to earth from the sky while everyone was watching. And with all the miracles he was allowed to perform on behalf of the first beast, he deceived all the people who belong to this world. He ordered the people to make a great statue of the first beast, who was fatally wounded and then came back to life. He was then permitted to give life to this statue so that it could speak. Then the statue of the beast commanded that anyone refusing to worship it must die. He required everyone—small and great, rich and poor, free and slave—to be given a mark on the right hand or on the forehead. And no one could buy or sell anything without that mark, which was either the name of the beast or the number representing his name. Wisdom is needed here. Let the one with understanding solve the meaning of the number of the beast, for it is the number of a man. His number is 666.