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Math Help - Help with math problem

  1. #1
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    Help with math problem

    Let F(n) be the number of occurrences of the digit zero in all the positive integers less than or equal to n. For example, F(9)=0, F(10)=1, and F(103)=14. With is F(800)?

    Is there an easier way than to just count all of them to solve this problem? Please help!
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  2. #2
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    May 2009
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    Well basically, you have 10,20,30,40,50,60,70,80,90,100=11 zeros and that is going to happen 8 times (210,220,230,...,780,790,800)

    Then you have 101,102,103,...,109 for a total of 9 zeros which happens 7 times

    So 8*11+7*9=151
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