Greek Numerals (Alphabetic Numbers)

The Greek alphabetic numeral system, also called Ionic or Milesian numerals, assigns a number to each letter of the alphabet plus three obsolete letters. Numbers from 1 to 999 are written by combining letters in descending value, much like Roman numerals — but more compactly, since Greek uses 27 distinct symbols where Roman uses only 7. The system has been in continuous use since the 4th century BCE and is still found today in chapter and section numbering, monarchs' titles (Constantine I = Κωνσταντίνος Αʹ), and Greek Orthodox liturgical texts.

How the System Is Built

The 27 numeric letters are organized in three groups of nine, each covering a power of ten:

• Units (1–9): α, β, γ, δ, ε, ϛ (stigma), ζ, η, θ
• Tens (10–90): ι, κ, λ, μ, ν, ξ, ο, π, ϟ (koppa)
• Hundreds (100–900): ρ, σ, τ, υ, φ, χ, ψ, ω, ϡ (sampi)

Three positions in the sequence are filled by letters that are no longer part of the alphabet but survive specifically for numerical use:

• 6 = ϛ (stigma) — a late-Byzantine ligature of σ + τ, often used in place of the older digamma Ϝ. Some traditions still write the digamma form.
• 90 = ϟ (koppa) — descended from Phoenician qoph; later survived as the Latin letter Q.
• 900 = ϡ (sampi) — added late to fill the final slot; its origin is uncertain.

The Keraia Mark

To distinguish numbers from words written with the same letters, Greek places a small mark called the keraia (κεραία, "little horn") after the letter or letter group:

• Upper keraia (ʹ, U+0374): Placed after letters to mark them as a number from 1 to 999. Example: ιαʹ = 11, τιεʹ = 315.
• Lower keraia (͵, U+0375): Placed before letters representing thousands. Example: ͵αωκδʹ = 1,824 (1000 × 1 + 800 + 20 + 4).

Numerals are constructed by combining letters in descending order of value with no zero placeholder needed — the system is additive, not positional. Place values are encoded by which letter is used, not by where it sits.

Complete Reference Table

Sigma's final form (ς) is never used in numerals — only the regular σ. The kappa (κ) and koppa (ϟ) look superficially similar in some fonts but represent different values (20 and 90).

Worked Examples

Numbers Above 9,999: The Myriad

For numbers from 10,000 upward, Greek mathematicians used the myriad (μυριάς, "ten thousand"). The myriad was written as Μ with a numeral above or beside it; for example, Μ^β meant "two myriads" or 20,000. Archimedes extended the system further in his treatise The Sand Reckoner, where he proposed orders of myriads to express genuinely astronomical figures — the number of grains of sand that could fill the universe — proving the Greek system was, in principle, unbounded.

Acrophonic (Attic) Numerals

Before the alphabetic system spread, Greeks used acrophonic numerals, based on the first letter of each number word: Π for πέντε (5), Δ for δέκα (10), Η for ἑκατόν (100), Χ for χίλιοι (1,000), Μ for μύριοι (10,000). This system, used in Athens until the 1st century BCE, parallels Roman numerals in its general approach.

Acrophonic numerals were eventually displaced by the alphabetic system because the latter is more compact and supports arithmetic more easily.

Modern Uses

Greek numerals are still encountered today in several contexts:

• Regnal numbers: Greek monarchs and Orthodox patriarchs use them (e.g. Παῦλος Αʹ, Paul I).
• Section and chapter numbering: In Greek legal documents and academic publications.
• Outline ordering: Similar to Roman numerals in English-language outlines.
• Ecclesiastical calendars: Years and feast days in Orthodox liturgical use.
• Naming conventions: School grades, military formations, and ship classes in Greece.

For more on the individual letters and their etymologies, browse our letter index, or read about the broader history of the Greek alphabet.