101 Dalmations!

Discrete Mathematics Level 4

Cruella De Vil has 15 dalmations captive. She wishes to cage them into 5 distinct cages, with each cage containing 3 puppies. If each dalmatian is distinct, and the number of ways Cruella can arrange the 15 dalmatians in each of the cages is $n$ , find the sum of the digits of $n$ .