^16-18 Then it compels all, small and great, rich and poor, free men and slaves, to receive a mark on their right hands or on their foreheads. The purpose of this is that no one should be able to buy or sell unless he bears the mark of the name of the animal or the number of its name. Understanding is needed here: let every thinking man calculate the number of the animal. It is the number of a man, and its number is six hundred and sixty-six.