If an integer n is to be selected at random from 1 to 400, inclusive, what is probability n(n+1) will be divisible by 8?  Choose the correct answer:
A) 1/4
B) 1/8
C) 1/2
D) 2/3
E) 3/4
For n(n+1) to be a multiple of 8, either n or n+1 has to be a multiple of 8.   Thus n must be of the form 8k or 8k-1.   The probability is 2/8 = 1/4.   The answer is 1/4.
<result>A</result>
If an integer n is to be selected at random from 1 to 400, inclusive, what is probability n(n+1) will be divisible by 8?