Answer
$\frac{1}{5,245,786}$
Work Step by Step
Because the order is not important, we can use the combination rule to determine the number of possibilities: $\frac{42!}{(42-6)!6!}=5,245,786$.
We also know that $probability=\frac{number \ of \ good \ outcomes}{number\ of\ all\ outcomes}$, therefore $P(success)=\frac{1}{5,245,786}$.