In a factory, one of the machines suddenly stopped working. The factory mechanic could not find fault, so the factory owner ranged up a renowned engineer to pay a visit and do the needful. The engineer arrived, studied the affected parts, asked for a hammer and gave one blow to one of the parts. Immediately the machine started working again. The next day engineer sent his bill for Rs. 1000.00.
The owner rejected the bill, arguing that the bill was astronomical given that all it took to rectify the situation was one blow with a hammer. The engineer then changed the bill as follows:
For hitting one blow with hammer-Rs. 10.00
For knowing where the hammer should be struck, Rs. 990.00