Lesson: Integer Properties Strategies

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Brent,

Could you help with the Exercise #161 of OG17?

Thanks,
Pedro
gmat-admin's picture

Glad to help!

Here's my step-by-step solution: https://gmatclub.com/forum/club-x-has-more-than-10-but-fewer-than-40-mem...

Cheers,
Brent

Brent,

Thank you!

Cheers,
Pedro

why is 51 not a prime number?
gmat-admin's picture

51 = 3 x 17
The sum of the digits = 5 + 1 = 6
Since 6 is divisible by 3, we know that 51 is divisible by 3

Cheers,
Brent

Hi! My question is pertaining to the rule regarding consecutive integers (N consecutive integers ==> 1 number must be divisible by N).... Does this mean that exactly 1 number within the list must be divisible by N, or at least one number (possibly more than 1?) must be divisible by N? I understood it as exactly 1 number must be divisible by N, but I just wanted to confirm.
gmat-admin's picture

Your interpretation is correct; in a set of N consecutive integers, exactly 1 of those integers is divisible by N.

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