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Can the positive integer k be expressed as the product . . .

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Can the positive integer k be expressed as the product . . .

by g3lo » Fri Jan 22, 2016 7:36 am
Can the positive integer k be expressed as the product of two integers, each of which is greater than 1?

I am having trouble understanding how this question implies that is K a prime number?

Couldn't the question be asking about a composite number as well? For example, positive integer K implies both composite or prime. Therefore;

4 X 5 = 20 (K)
2 X 6 = 12 (K)

All numbers greater than 1 and K can be expressed as the product of 2 integers, each of which is greater than 1.

What am I missing?
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Source: — Data Sufficiency |
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by g3lo » Fri Jan 22, 2016 8:28 am
Never mind, I figured it out. Foolish me. It is essentially asking if K is a composite number or non-prime number.

If K = Prime, than you would require a 1 in one of the factors for the product to equal that prime number (k). Therefore, it must be true that the question is relating to a composite number.
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by [email protected] » Fri Jan 22, 2016 11:47 am
Hi g3lo,

When dealing with DS questions, it might be tempting to take a 'theory-based' approach, but you'll likely find it far more useful to TEST VALUES and assemble 'proof' of what options are available. DS questions 'test' a variety of different skills, including organization, accuracy, attention-to-detail, thoroughness, etc. If you only 'see' one possible outcome, but there is another, then you'll get the question wrong (and you won't even realize it). The 'math' required to answer most DS questions is relatively simple, so don't be afraid of putting the pen on the pad, asking "what if...", and writing down the possibilities.

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Rich
Contact Rich at [email protected]
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by Matt@VeritasPrep » Fri Jan 22, 2016 3:42 pm
g3lo wrote:Never mind, I figured it out. Foolish me. It is essentially asking if K is a composite number or non-prime number.

If K = Prime, than you would require a 1 in one of the factors for the product to equal that prime number (k). Therefore, it must be true that the question is relating to a composite number.
Yup, you've got it. Prime numbers can only be expressed as 1 * p, so they can't be expressed as the product of two integers > 1. So the question is asking "Is k a composite integer?" ... which is just the flipside of "Is k prime?"
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