The event "not rolling 1, 3, 4, or 5" is the same event as "rolling 2 or 6".
Since the possible outcomes of a number cube have the same probability, the probability of rolling 2 or 6 is given by
[tex]\dfrac{\text{\# of good outcomes}}{\text{\# of possible outcomes}}=\dfrac{2}{6}=\dfrac{1}{3}[/tex]