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DominicanKing
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If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 24. What is the value of r?
(1) n is not divisible by 2
Let’s say that n = 5, the remainder will be 0
Let’s say that n = 3, the remainder will be 8
Insuff
(2) n is not divisible by 3
Let’s say that n=2, the remainder will be 3
Let’s say that n=5, the remainder will be 0
Insuff
1&2
We need numbers that are not divisible by 2 or 3 so let’s try 1, 5, 7, 11
When n = 1, the remainder is 0
When n=5, the remaineder is 0
When n=7, the remainder is 0
When n=11, the remainder is 0
The remainder is always 0 when n is not divisible by 2 and 3.
SUFF
I choose C
well done
