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Math Help - which numbers are prime

  1. #1
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    which numbers are prime

    which numbers are prime?

    a. 667

    b. 557

    i tried using numbers like (23)^2

    and (24)^2

    I didn't know how to prove this. Please show what needs to be done.
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by rcmango View Post
    which numbers are prime?

    a. 667

    b. 557

    i tried using numbers like (23)^2

    and (24)^2

    I didn't know how to prove this. Please show what needs to be done.
    Try factoring them.

    For example, divide 667 by 2. It gives a decimal. So try 667/3, 667/5, 667/7 until you get to about \sqrt{667}. If you have no factors yet, then the number is prime.

    I get that 557 is prime and 667 is composite.

    -Dan
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  3. #3
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    okay, 667 = 23 * 29

    thankyou for the help.
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