There was an engineer who had an exceptional gift for fixing all things
mechanical.
After serving his company loyally for over 30 years, he happily retired.
Many years later the company contacted him regarding a seemingly
impossible problem they were having with one of their multimillion dollar
machines.

They had tried everything and everyone else to get the machine to work but
to no avail.
In desperation, they called on the retired engineer who had solved so many of
their problems in the past.
He spent a day studying the huge machine.
At the end of the day, he marked a small “x” in chalk on a particular
component of the machine and stated,
“This is where your problem is.”
The part was replaced and the machine worked perfectly again.
The company received a bill for $50,000 from the engineer for his service.
They demanded an itemized accounting of his charges. The engineer
responded briefly:

“One chalk mark $1. Knowing where to put it $49,999”