Number of states in classical planning
You're both wrong.  It should be $10^{50} \times (10+50)^{200}$.  If you have $k$ objects, and there are $n$ possible places for each, there are $n^k$ possible combinations of ways for where to put each of them.

This probably doesn't really change the main point that I suspect the AI book was making: there are a lot of possible states, far too many to iterate over one by one.