Many thanks to Robert Simons for this question:

"I am exactly n times my daughter's age. In m years I shall be exactly (n-1) times her age. In m ² years I shall be exactly (n-2) times her age. After that I shall never again be an exact multiple of her age. Ages, n and m are all whole numbers. How old am I?

Now suppose there is some wishful thinking in the above assertion and I have to admit to being older, and indeed that I will be an exact multiple of her age in m ³ years. How old does this make me?"