Ghost the Bunny
Laura’s pet bunny, Ghost, hops up a flight of 12 stairs. Ghost can hop up one or two steps at a time, and never hops down. How many ways can Ghost reach the top?
(note, if Ghost goes up one at a time, and ends with a double hop, or if he starts with a double hop, then goes up the rest one at a time, those count as two different ways) (iow, order matters.)
If 12 steps is too challenging, solve for a smaller number.
And if you solve this easily, try to find a second or a third method. (I have three)
Finally, I believe this puzzle has been around in various forms for years, but I believe I ran into the bunny version about ten years ago at a talk by Al Posmentier, Professor of Mathematics Education (and now Dean of Education) at CCNY.
I only found 3 bunnies on stairs via google (excluding playboy bunnies and girls named bunny).