I was playing in a D&D game with my boy last Sunday, and someone brought up the question of how likely a character was to have an 18 stat. Of course the rest of the session was a loss for me, as I sat there trying to do the math with pencil, paper, and a four-function calculator.
D&D has six stats, each a number between 3 and 18. The character roll-up rules we are playing specify that each stat will be obtained by rolling four dice and taking the top three.
About 9% of D&D characters will have an 18 stat. The answer is explained here. (B)