"Céad faoin gcéad."
Pretty much. Think of it as roughly "out of a hundred" (which is what percent means as well)
Ah cool! Now when i say maith thú to people for understanding or speaking giota beag gaeilge, i can add céad faoin gcéad to that too!
How about adding "a" to make it "a hundred percent"? This is how it would be spoken.
Ditto. I can't think of an instance where Americans don't say a hundred. Is this not true in Ireland?