The manager of a fancy hotel gets an urgent call from maintenance. "The pipes are going crazy, the basement is flooding!" Not missing a beat, he calls a highly recommended expert plumber.
The plumber shows up, and they both go downstairs. Sure enough, the pipes have burst, water is spraying everywhere, and it's already three feet deep. The plumber walks over to the central unit. He takes a minute to look around, then calmly takes out his hammer and gives it a single whack. Instantly the water stops shooting everywhere, and begins to drain. Everything is back to normal.
The manager thanks him profusely and asks for the bill. The plumber hands it to him. "$10,000."
"WHAT?" the manager says. "All you did was come down here whack the thing with a hammer. How can that be $10,000??"
The plumber responds, "Oh. I can give you an itemized bill if you want."
The manager agrees, and the plumber writes a new one. "Price to come down and whack the thing with a hammer: $100. Consulting fee—knowing exactly where to whack—$9,900."
