MathDB

2018 PUMaC Combinatorics B1

Source:

December 8, 2018

probabilityrelatively primecombinatoricsnumber theory

Problem Statement

You have four fair

6

-sided dice, each numbered

1

6

(inclusive). If all four dice are rolled, the probability that the product of the rolled numbers is prime can be written as

\tfrac{a}{b}

, where

a

and

b

are relatively prime. What is

a+b