Rev 13:18 This calls for wisdom: Let the one who has insight calculate the beast’s number, for it is man’s number, and his number is 666.

There have been two main ways of explaining this number.

1. The number of Nero

This is been the identification traditionally and in much recent scholarship.

In Greek and Hebrew, numbers were written using letters of the alphabet in the 1st century, and in that language the letters making up ‘Nero Caesar’ add up to 666.

According to Koester, the word translated ‘calculate’ (psēphizein) is precisely the word that was used for the adding up of numerical values of letters of the alphabet.

Clint Burnett thinks that inscriptional evidence supports the identification of this number with Nero:

One of the most interesting things about name calculations is that Latin speakers participated in the practice. However, given that the letters of the Latin alphabet did not function as numbers but that Latin speakers had Roman numerals, Latin speakers had to express their name calculations in Greek. Thus, Latin speakers who made name calculations in graffiti expected those who read them to calculate the names in question not in Latin but in Greek—there appears to be a wide assumption that these inscriptions will be read and interpreted bilingually.

These observations help us to make sense of the number of the beast in Rev 13:18 because John the prophet provides enough information for his audience to decipher 666 as the name calculation Nero Caesar. His most explicit account of imperial divine honors in the book prefaces his reference to the beast and his number (Rev 13:4, 8, 12, 15). With his reference to one of the heads of the beast with ten diadems and blasphemous names that received a death blow that was healed (Rev 13:3), he alludes to the myth that was circulating in the late first century AD that Nero would return from the dead. Just as Latin speakers expected their audiences to calculate their name calculations in Greek, John expects his audience to transliterate the number from Greek to Hebrew/Aramaic, which means that it would lack vowels—he makes the same assumption that his readers will read and interpret bilingually. Thus, Νέρων Καῖσαρ in Greek letters must become nrwn qsr in Hebrew letters, which calculates to 666: n = 50 + r = 200 + w = 6 + n = 50 + q = 100 + s = 60 + r = 200 = 666.

Mounce, however, says that this solution

‘asks us to calculate a Hebrew transliteration of the Greek form of a Latin name, and that with a defective spelling.’

Ladd and others point out that this requires a variant spelling, and in any case it is difficult to see why the Hebrew should be recalled when the book itself was written in Greek. Cf. Rev 17:9.11.

Ladd further notes that no ancient interpreter of Revelation made this identification.  Irenaeus thought that 666 might represent lateinos (the Latin Empire); Ladd and others find this plausible.

Michaels observes that, with a little ingenuity, many names – ancient and modern – might be represented by the number 666.  (‘Hitler’ is one good candidate, if A=1, B=2, C=3 etc!)

Some ancient manuscripts have the number as 616.  It is possible, according to Mulholland and others, that this variant found its way into the textual tradition as an adaptation of the gematria for readers whose primary language was Latin, in which language 616 would represent ‘Nero Caesar’.

2. The number of imperfection

More simply, six, being one short of seven, represents a falling short, a missing the mark, a failure. 666, then, stands for failure upon failure upon failure.

For Hendriksen, the numbers means ‘failure upon failure upon failure’.

For Ladd, the number 666 might symbolize ‘the best that man can do’.  This might be what is meant be the expression ‘it is a human number’.

Beasley-Murray (NBC):

‘For Christians, 666 was an eminently suitable figure for the antichrist; it represents a consistent falling short of the divine perfection suggested by 777, whereas the name Jesus in Greek totals 888! Therein lies one aspect of the difference between the devil’s christ and the Christ of God: the pseudo-christ falls as far short of being the deliverer of the world as the Christ of God exceeds all the hopes of humankind for a Saviour.’

Ian Paul suggests that even without the letter/number system 666 would have been significant to early readers.  Since 7 symbolises completeness, 6 represents a falling short.  Moreover, 666 is a triangular number (yielding an equilateral triangle of side 36).  As for a specific referent, Ian Paul, like many others, opts for Nero.

Some, including Wright (Revelation for Everyone) embrace elements of both explanations, suggesting that the number is not only a cryptogram but also a parody.

It would seem, with our present level of knowledge, that it is best to avoid dogmatism on the precise meaning of the number 666.