I have been reading a book called Eolas ar Áireamh - arithmetic tables in Irish by Peadar Ua Laoghaire. I have found lots of interesting things on numerals, and also a nice Irish jingle to remember the number of days in the months (similar to the English "30 days hath September..." jingle): see http://www.corkirish.com/wordpress/arithmetic-in-irish .

I've explained in more detail there, but the jingle is:

NA LAETHEANTA INS GACH MÍ


Tríochad lá a bheirid leó
Samhuin, Abrán, na Mithimh teó.
Lá sa mbreis ag gach mí eile,
Acht an Feabhra thiar ar deire,
Gan aige acht ocht lá fhichid -
Naoi lá fhichid, i mbliaghain bhisig.