I liked both actually, and I have one of my own
An engineer and a mathematician are in a race of who can surround a large number of cows while using at least material to make a fence as possible.
The engineer struggles all day to stack the cows as close as possible in a round formation, then builds a tight fence around them.
The mathematician takes a few pieces of wood, and builds a small ragged-tagged fence around his own feet, and then says:
"I define myself as being on the exterior."