is the sequence of letters of an alphabetic script established for mnemonic reasons, in particular to the Phoenician abgad (i.e. beginning with Aleph-Beth-Gimel-Dalet) that was adopted by the Greeks as Alpha-Beta and by the Romans as ABC. Letters have had numerical value (according to their sequence in the alphabet) only since Hellenistic times.
J. Naveh, Early History of the Alphabet, 1982
B. Sass, Studia Alphabetica, OBO 102, 1991
E.A. Knauf, Die Umwelt des Alten Testaments, NSK AT 29, 1994, 212–221.