The Greek Numeral Table and Isopsephic Sums

Classical Greek used its own alphabet for ordinary counting rather than a separate numeral system, and isopsephy simply applies that existing numeral table to words. The twenty four letters taught in school run Alpha at 1 through Omega at 800, but the counting table itself was never limited to twenty four symbols: three archaic letters that had dropped out of the spoken alphabet by the classical period, digamma or stigma for 6, koppa for 90 and sampi for 900, were kept on for arithmetic alone, so that every value from 1 to 900 had a single dedicated symbol rather than requiring combinations, unlike the later positional systems that replaced it.

To find a word's isopsephic value, each letter's numeral value is simply added to the running total; a personal name, a divine epithet or a short phrase all reduce to one sum by the same operation. Two words or phrases sharing an identical total were read in antiquity as bound together in meaning, a form of wordplay that shows up in inscriptions, graffiti and literary riddles from the Hellenistic period onward, and the practice runs in close parallel to Hebrew gematria, which performs the identical operation on a different alphabet within a separate cultural and religious tradition.