It has traditionally been assumed that the Greek alphabetic numerals were independently invented in the 6th century BC. However, the remarkable structural similarity of this system with the Egyptian demotic numerals used at the time has hardly been noted. The origin of the alphabetic numerals among Ionian traders who doubtless knew of the demotic numerals, especially given the Ionian colony at Naukratis in the Nile Delta, provides the historical context for postulating diffusion of the numerals from Egypt to Greece. It is proposed that the theory of independent invention of the alphabetic numerals be replaced with a working hypothesis of direct diffusion from the Egyptian demotic numerals.