After aon, nouns starting with B, C, F, G, M and P lenite: aon bhòrd, aon chidsin, aon gharaids. D, S and T can lenite of course, but tend not to after the letter N, so we say: aon doras, aon seòmar, aon taigh.
The t in the the word taigh is too strong to lenite! You will often find this is the case when an n and t meet! This also happens if s is followed by a vowel.
The noun after number two always takes the singular and lenites if possible.
The noun after number three always takes the plural.