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by Rahul@gurome » Wed Dec 22, 2010 10:18 am
Woozler wrote:109) If p is positive integer, what is remainder when p is divided by 4?
a. When P is divided by 8 remainder is 5
b. P is the sum of the squares of two positive integers.
Statement 1: When p is divided by 8 remainder is 5.
Thus p must be of the form (8n + 5), where n is a non-negative integer.
Thus, p = (8n + 5) = (8n + 4 + 1) = 4(2n + 1) + 1
Therefore when p is divided by 4, remainder is 1.

Sufficient.

Statement 2: p is the sum of the squares of two positive integers.
Thus p must be of the form 2(n² + m²), where n and m are positive integers.
If n and m both are even, p is divisible by 4 => remainder = 0
If n and m both are odd, p is not divisible by 4 => remainder may is 1 or 2 or 3

Not sufficient.

The correct answer is A.
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by Woozler » Wed Dec 22, 2010 10:29 am
"Thus p must be of the form (8n + 5)"

God, I keep forgetting about this form when it comes to divisibility. I got the question right (A) but it was more of an educated guess.

Anyway, Rahul, if I'm getting 49-50 on quant GMAT, you will be the sole person responsible for my progress. Thank you for all the work you've done on this forum.

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by Rahul@gurome » Wed Dec 22, 2010 10:33 am
My pleasure Woozler! :)
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