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Math Help - Basic Counting Principles

  1. #1
    DBA
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    Basic Counting Principles

    How many times is the digit 5 written when listing all numbers from 1 to 100000?
    a)4 b)5x10^4 c) 1+10+100+1000

    The correct answer is b but I do not understand why.

    I thought it is c because 1 to 10 have 1 five, the 11-100 have 1+10 fives.

    Thanks for any help that explains the answer of 5x10^4.
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  2. #2
    Super Member TheChaz's Avatar
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    Think about a number of this form...
    5x,xxx.
    How many are there? There are 10 options for each "x", so 10^4...

    This reasoning would at least eliminate the other answer choices.
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