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Math Help - divisors

  1. #1
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    divisors

    How many numbers from 1 to 18,000, inclusive, are divisible by 20 or 3 or both?
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  2. #2
    MHF Contributor chiph588@'s Avatar
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     18000 = 900\cdot20

    So all the multiples of  20 are  \{1\cdot20,2\cdot20,3\cdot20,\cdots,900\cdot20\}

    Hopefully you can see how many elements are in that set.

    The case with  3 follows the same way.
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