One day recently, while our little girl and boy cats, er, I mean two boy cats, were at the mobile clinic having their manhood removed, I had the Princess take a slight detour from her normal math curriculum, after she asked why we were having them "fixed".
I set her up with this problem: If a cat gave birth to 5 cats each year, and each of those cats gave birth to five cats each year (and so on), how many cats would there be in 10 years?
Remember, each of the cats has 5 babies each year, so in year 1 there is 1 parent, in year 2 there are 6 parents, in year 3 there are 36, etc. This of course assumes that they are not mating with each other.
And the answer...
110 million cats is a lot of cats. Princess still wishes we could have kittens, but now she understands.