Remember that math game 24 from middle school? It's the one where you are given 4 numbers and you have to do basic math operations (+,-,*,/) to make the 4 numbers equal 24. For example, if I had the numbers 2,3,4,5 I could get to 24 by doing 2*(5+4+3) or maybe by doing 4*(5+3-2). You get the idea.
So the game itself is pretty simple and for some reason I find myself playing it with the numbers on a clock or credit card or something else when I am bored. And I was finding that it was normally pretty easy to find a solution given any set of numbers. That made me start to ask a couple of questions.