2021 USMCA National Championship #4
Source:
May 9, 2021
Problem Statement
I roll three special six-sided dice. Each die has faces labeled U, S, M, C, A, or *. The star can represent any of U, S, M, C, A. What is the probability that I can arrange the dice to spell out USA? (For instance, A*U is valid, but UU* is not valid.)