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.
The Minoan and Mycenaean civilizations‘ Linear A and Linear B alphabets used a different system, called Aegean numerals, which included number-only symbols for powers of ten: 𐄇 = 1, 𐄐 = 10, 𐄙 = 100, 𐄢 = 1000, and 𐄫 = 10000.
Attic numerals comprised another system that came into use perhaps in the 7th century BCE. They were acrophonic, derived (after the initial one) from the first letters of the names of the numbers represented. They ran = 1, = 5, = 10, = 100, = 1,000, and = 10,000. The numbers 50, 500, 5,000, and 50,000 were represented by the letter with minuscule powers of ten written in the top right corner: , , , and . One-quarter was represented by
𐌂 (right half of a full circle) and one-half by the left side of the circle. The same system was used outside of Attica, but the symbols varied with the local alphabets, for example, 1,000 was in Boeotia.
The present system probably developed around Miletus in Ionia. 19th century classicists placed its development in the 3rd century BCE, the occasion of its first widespread use. More thorough modern archaeology has caused the date to be pushed back at least to the 5th century BCE, a little before Athens abandoned its pre-Euclidean alphabet in favour of Miletus‘s in 402 BCE, and it may predate that by a century or two. The present system uses the 24 letters used by Euclid, as well as three Phoenician and Ionic ones that had not been dropped from the Athenian alphabet (although kept for numbers): digamma, koppa, and sampi. The position of those characters within the numbering system imply that the first two were still in use (or at least remembered as letters) while the third was not. The exact dating, particularly for sampi, is problematic since its uncommon value means the first attested representative near Miletus does not appear until the 2nd century BCE, and its use is unattested in Athens until the 2nd century CE. (In general, Athenians resisted using the new numerals for the longest of any Greek state, but had fully adopted them by c. 50 CE.)