A mainframe computer on which everyone in the office depended suddenly went down. They tried everything but it still wouldn't work. Finally they decided to call in a high-powered computer consultant.

He arrived, looked at the computer, took out a small hammer and tapped it on the side. Instantly the computer leapt back to life. Two days later the office manager received a bill from the consultant for $1,000.

Immediately he called the consultant and exclaimed, "One thousand dollars for fixing that computer?! You were only here five minutes! I want the bill itemized!"

The next day the new bill arrived. It read, "Tapping computer with hammer: $1. Knowing where to tap: $999."