Tuesday, October 12, 2010

How many Zeroes - One puzzle a day - Puzzle Buddies

Puzzle: A certain street has 1000 buildings. A sign maker is contracted to number the houses from 1 to 1000. How many zeros will the sign maker need

Note: Don't forget to visit us again. Answer to the puzzle will be posted tomorrow.

Solution:

Divide 1000 building numbers into groups of 100 each as follow: (1..100), (101..200), (201..300),....... (901..1000) For the first group, sign-maker will need 11 zeroes.
For group numbers 2 to 9, he will require 20 zeroes each.
And for group number 10, he will require 21 zeroes.
The total numbers of zeroes required are
= 11 + 8*20 + 21
= 11 + 160 + 21
= 192

Winner: None

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