A physicist, an engineer, and a mathematician are all locked in different burning buildings.

The physicist calculates exactly how much water he will need to put out the fire, runs and finds that amount, puts out the fire, and survives.

The engineer calculates exactly how much water he will need to put out the fire, runs and finds 10 times that amount, puts out the fire, and survives.

The mathematician calculates exactly how much water he will need to put out the fire and declares, “There IS a solution!”, and then burns to death.