If three, standard, 6-faced dice are rolled, what is the probability that the sum of the face up integers is 16?
The only possible combinations are
5 5 6
5 6 5
6 5 5
So the probability is 3/6^3 = 1/72.
There are 63=216 ways to roll the dice
There are only 2 ways to get 16: (5,5,6), (4,6,6)
In both cases, there are 3!÷2!=3 ways to order them
Thus, the probability is 2×3216=6216=136