Probability Three Dice Sum To 18

To get 18, we would have to get six three consecutive times. The probability of this is 1 over 6 to the third power, which is 1 in 216.

To put that in perspective, suppose you raise a spade card of the 13 on the card deck. The chance of raising twice the same card is 1 in 169, which is a bit more likely than 1 in 216.

The only combination that equals 18, is 6+6+6.
There are $6^3=216$ possible combinations, so $\frac{1}{216}$ .