If R is an integer greater than 6, which of the following must be divisible by 3?
Choose the correct choice from the following answers.
A) R(R+1)(R-4)
B) N(N+2)(N-1)
C) N(N+3)(N-5)
D) N(N+4)(N-2)
E) N(N+5)(N-6)
Now take R = 3k , R = 3k+1 R = 3k+2..put in all the choices. If by putting all the values of R we get it is divisible by 3, then it is correct answer choice.   A is correct. It will hardy take 10 sec per choice as we have to consider only 3k+1 and 3k+2.
<result>A</result>
If R is an integer greater than 6, which of the following must be divisible by 3?