A.T. Robertson Commentary Revelation 13:17

"and that no man should be able to buy or to sell, save he that hath the mark, [even] the name of the beast or the number of his name." — Revelation 13:17 (ASV)

That no man should be able to buy or to sell (ινα μη τις δυνητα αγορασα η πωλησα). Final clause with ινα and present middle subjunctive of δυναμα with aorist active infinitives. This is a regular boycott (Ramsay, Seven Letters, p. 106f.) against all not worshippers of the emperor.

Save (ε μη). "If not," "except."

Even the name (το ονομα). No "even," just apposition with χαραγμα (the mark).

Or the number (η τον αριθμον). The stamp (the mark) may bear either the name or the number of the beast. The name and the number are one and the same. They could write the name in numerals, for numbers were given by letters. Swete suggests that it was "according to a sort of γεματρια known to the Apocalyptist and his Asian readers, but not generally intelligible."