Revelation 13:17-18

New King James Version

¹⁷ and that no one may buy or sell except one who has ^[a]the mark or ^(A)the name of the beast, ^(B)or the number of his name.

^18 (C)Here is wisdom. Let him who has ^(D)understanding calculate ^(E)the number of the beast, ^(F)for it is the number of a man: His number is 666.