Isopsephy or isopsephism is the practice of adding up the number values of the letters in a word to form a single number. The total number is then used as a metaphorical bridge to other words evaluating the equal number, which satisfies isos or "equal" in the term. Ancient Greeks used counting boards for numerical calculation and accounting, with a counter generically called psephos ["pebble"], analogous to the Latin word calculus, from which the English calculate is derived.

Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal numbers and in contexts similar to those in which Roman numerals are still used in the Western world. For ordinary cardinal numbers, however, modern Greece uses Arabic numerals.