If n is a positive integer and r is the remainder when (n1)(n+1) is divided by 24, what is the value of r?
1). n is not divisible by 2
2). n is not divisible by 3
Please explain?
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 logitech
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If n is a positive integer and r is the remainder when (n1)(n+1) is divided by 24, what is the value of r?
1). n is not divisible by 2
So n is an odd number
n=1  0
n=3  8
n=5  0
INSUF ( I did not catch the n=3 case before )
2). n is not divisible by 3
n=1  0
n=2  3
Insuf
Together we know that n can not be 3 and n will be an ODD number
1, 5, 7, 11 and for all of these number the remainder will be 0
Choose C
1). n is not divisible by 2
So n is an odd number
n=1  0
n=3  8
n=5  0
INSUF ( I did not catch the n=3 case before )
2). n is not divisible by 3
n=1  0
n=2  3
Insuf
Together we know that n can not be 3 and n will be an ODD number
1, 5, 7, 11 and for all of these number the remainder will be 0
Choose C
Last edited by logitech on Mon Jan 19, 2009 9:52 am, edited 1 time in total.
LGTCH

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 logitech
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If n is a positive integer and r is the remainder when (n1)(n+1) is divided by 24, what is the value of r?yalanand wrote:Logitech could you please explain me about this ??
1). n is not divisible by 2
So n is an odd number
n=1  0
n=3  0
n=5  0
So We will always get 0 as a remainder SUF
How is this sufficient ??
So we are asked to find the remainder. And in the first statement we all have 0 as the remainder when the number is divided by 24.
For example n=5
(n1)(n+1) = 4x6=24 divided by 24 , remainder is 0
Now looking at my previous post, I realized that the only ODD number that will leave a different remainder is n=3
2x4=8 and when is divided by 24 , the remainder is 8
So it seems like A can not be sufficient because of the n=3 case.
Let's say what other will have to say :roll:
LGTCH

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