A new street is built

Apr 7, 2008
4,909
3
0
A new street is built with one hundred new houses, numbered 1 to 100. How many number 9's are required to number all the houses?
 
Apr 7, 2008
4,909
3
0
Crisbee

Got it ....... @ 06.01 am

Not 10 (people forget the 90), not 11 (people forget the 90's): The answer is 20: 9,19,29,39,49,59,69,79,89,90,91,92,93,94,95,96,97,98,99(99's 1st digit),99(99's 2nd digit).
 

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