Answer:
Not enough information for a complete answer. The total time asleep is needed. See below for the approach.
Explanation:
We know a cat sleeps 1/3 of an hour at a time. We need to know how much time the cat sleeps for the period in question. It kitty slept a total of 6 hours, then it would have taken:
(6 hours)/(1/3 hour/nap)
6/(1/3) = 6(3/3) = 18 naps in 6 hours