A good answer might be:

You may destroy the rock by pounding it with a hammer.

Pounding a Rock to Dust

You have a rock. You have a hammer. The size of the problem "destroy the rock" may be made smaller by applying the hammer to the rock.

Click on the Image to Apply Recursion

After applying the hammer, you now have several smaller problems. Each of these smaller problems may be solved by applying the hammer.


When do you stop applying the hammer?