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Math Help - factors

  1. #1
    Newbie pinky&thebrain's Avatar
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    factors

    how do i know if 7 is a factor of 5^2 * 31 * 43 * 10^6
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  2. #2
    Senior Member OReilly's Avatar
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    Quote Originally Posted by Pinky&The Brain View Post
    how do i know if 7 is a factor of 5^2 * 31 * 43 * 10^6
    You can calculate that expression and see if its divisble by 7.

    So 5^2 * 31 * 43 * 10^6=33325000000 and divide that by 7 to see if integer comes up.

    But another simpler way to see that 7 isn't factor is by looking at all factors at expression. So from expression we have factors 5,31,43 and 10 so 7 isn't factor.
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  3. #3
    Grand Panjandrum
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    Quote Originally Posted by Pinky&The Brain View Post
    how do i know if 7 is a factor of 5^2 * 31 * 43 * 10^6
    As 7 is prime, if it is a factor of a product then it divides (is a factor of) at
    least one of the terms of the product.

    In this case if 7 is a factor of 5^2*31*43*10^6 it must be a factor of one
    of:

    5, 31, 43, 10,

    which it is not so it is not a factor of 5^2*31*43*10^6.

    Alternatively, break the product down to a product of prime factors,
    if 7 appears among the list of prime factors then the 7 is a factor
    of the product, otherwise it is not (the prime factorisation is unique
    by the fundamental theorem of arithmetic).

    RonL
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  4. #4
    Newbie pinky&thebrain's Avatar
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    Thank you both very much for helping!!!!! I appriciate it....
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