The number of ways of selecting 4 cards of an ordinary pack of playing cards so that exactly 3 of themare of the same denomination is

We can choose one denomination in  13C1 ways, then 3 cards of this denomination can be chosenin  4C3 ways and one remaining card can be chosen in  48C1 ways. Thus, the total number of choices is 13C1 4C3 48C1=13×4×48=2496.