[From We Dare You To Solve This! by John Paul Adams.]
When I saw Madder, he was part way up a ladder. He went up four rungs, down seven rungs, and up ten. That put madder at the top of the ladder.
Then he went down nine rungs, up three rungs and down ten. That put him at the bottom of the ladder, that is, with his feet on the ground.
How many rungs has Madder's ladder?