Irish Gaelic: Numbers and Counting
Like English, there are several forms of numbers (for counting one, two, three; for ranking things first, second, third; etc). In addition, Irish has some special forms for counting people.
The standard 'counting numbers' are:
The 'a' in front of number is often omitted. It is required, however, when counting out loud, when saying an address, and when calling out numbers, like a phone number. Using 'a' adds an 'h-' (remember lenition?) to numbers that begin with a vowel aon (one) and ocht (eight).
Counting things requires a few changes.
Rule 1: The singular form of the thing being counted is used.
Rule 2: The numbers one, two, and four change form for counting things.
As you can see, there are some changes to the words being counted.
When counting things greater than 10, the name of the thing being counted is put between the numbers:
Counting greater than 20 things can be done in one of two ways:
seasca is a cúig punt 75 pounds, lit. seventy and five pounds, or
Counting people is different yet again. The standard 'counting numbers' are not used for people.
Rule 1: beirt (two people) causes lenition.
Finally, ordinal numbers (first, second, third) are slightly different as well.
These cause a few changes, too.