How many 7-card hands can be dealt having exactly 3 of a kind?
I think the answer is $13\times{4\choose 3}\times{48\choose 4} = 10118160$. Can anyone verify?
13 is for the possibilities of the rank of the 3 of a kind, {4\choose 3}${4\choose 3}$ is for the selection of 3 cards from that rank, and {48\choose 4}${48\choose 4}$ is for the selection of the remaining 4 cards from the 48 cards that are not in the selected rank.