- ‘ο ’έχων τον νούν, ψηφισάτω τον ’αριθμον τού θηρίου· ’αριθμος-γαρ ’ανθρώπου ’εστιν, και ‘ο-’αριθμος-’αυτού χξς.
- He who has understanding [or "a mind"] let him count the number of the beast: for a man's number it is, and its number [is] 666.
The number found in most manuscripts and modern translations of the Greek text is 666, although various modern studies show the number could be 616 based on Papyrus 115 from the third century.  The most widely accepted theory connects the cryptogram of the Greek numerals to the letters of the alphabet, since numbers in ancient Greek were represented by letters. Gematria, a type of cryptogram that assigns numerical values to alphabetic characters, is one form of these numerological exercises. The numeral 666 (DCLXVI in Roman numerals which like Greek represents numbers with alphabetic letters) in ancient Greek was represented as χξς Chi, Xi, and Vau. The mainstream consensus among biblical scholars is that 666 is a reference to the emperor Nero which, according to which language and schema one uses, can be rendered as either "666" or "616."
There are three different characteristics that distinguish the beast according to Revelation 13:16 to 18 - His mark (of authority), His name and the number of his name (666). It might be argued by some that 666 must be applied to one man's name, and that this will then help identify him as the Antichrist. Others claim that the following verse shows that 666 need not apply solely to a man's name:
- And he hath on his vesture and on his thigh a name written, KING OF KINGS, AND LORD OF LORDS. (Rev. 19:16)
The same Greek word translated as name (onoma) that appears in Revelation 13:17-18 is also used in chapter 19:16, so the word could possible apply to a title, and not just one man's name.
- St. Irenaeus of Lyons in the 4th century discusses this in his famous work.