Learn Irish Numbers
This page covers the modern decimal system (córas deachúlach) for counting in Irish. The numbers shown here are the standalone abstract form (with the a particle) used when reciting numbers without a noun — the form taught in school and used for phone numbers, maths and the like. The historical vigesimal system (trí fichid = 60) is not used in the quiz.
1–10: a haon, a dó, a trí…
Each number takes the particle a in front. Vowel-initial numbers (1 aon, 8 ocht) get an h-prefix after the particle:
- 1 = a haon
- 2 = a dó
- 3 = a trí
- 4 = a ceathair
- 5 = a cúig
- 6 = a sé
- 7 = a seacht
- 8 = a hocht (h-prefix on the vowel)
- 9 = a naoi
- 10 = a deich
11–19: adding déag
The teens are the digit + déag (“-teen”). One quirk: after a dó, déag lenites to dhéag:
- 11 = a haon déag
- 12 = a dó dhéag (lenited)
- 13 = a trí déag
- 14 = a ceathair déag
- 15 = a cúig déag
- 16 = a sé déag
- 17 = a seacht déag
- 18 = a hocht déag
- 19 = a naoi déag
20–99: tens with the a connector
The tens drop the a particle. Each one is its own word:
- 20 = fiche
- 30 = tríocha
- 40 = daichead
- 50 = caoga
- 60 = seasca
- 70 = seachtó
- 80 = ochtó
- 90 = nócha
For compounds, put the unit after the tens with a as a connector:
- 21 = fiche a haon
- 47 = daichead a seacht
- 99 = nócha a naoi
Quick check: 22, 58, 86?
22 fiche a dó · 58 caoga a hocht · 86 ochtó a sé
Hundreds: lenition & eclipsis
The word for 100 is céad. Multipliers 1–6 trigger lenition (c → ch); 7–9 trigger eclipsis (c → gc):
- 100 = céad
- 200 = dhá chéad (lenited)
- 300 = trí chéad
- 400 = ceithre chéad
- 500 = cúig chéad
- 600 = sé chéad
- 700 = seacht gcéad (eclipsed)
- 800 = ocht gcéad
- 900 = naoi gcéad
Combine with tens and units the usual way:
- 134 = céad tríocha a ceathair
- 365 = trí chéad seasca a cúig
Thousands & millions
Míle (1000) and milliún (1,000,000) follow the same lenition pattern as céad. m isn’t affected by eclipsis, so 7–9 stay as plain míle/milliún:
- 1,000 = míle
- 2,000 = dhá mhíle
- 3,000 = trí mhíle
- 5,000 = cúig mhíle
- 7,000 = seacht míle (no mutation)
- 10,000 = deich míle
- 100,000 = céad míle
- 1,000,000 = milliún
- 5,000,000 = cúig mhilliún
Larger compounds simply chain together:
- 1,234 = míle dhá chéad tríocha a ceathair
Common mistakes
- Where the a goes: 1–19 begin with a; 20+ don’t. But a reappears between tens and units in compounds: fiche a haon, not “fiche haon”.
- Lenition vs. eclipsis on céad: 1–6 lenite (dhá chéad), 7–9 eclipse (seacht gcéad). Same pattern for míle/milliún, except m doesn’t take eclipsis — so seacht míle, not “seacht bp…”.
- Don’t use beirt/triúr: those are for counting people, not for abstract numbers. The quiz uses the abstract form (a haon, a dó…).
- Lenited déag only after dó: it’s a dó dhéag (12), but a trí déag (13) without lenition.