You guys are right; the digit after the decimal point is the tens digit, not the units digit. My bad and thanks for the correction!

The answer is B. 8x will always yield a non zero tenth digit.

I see in Tatianas explanation, she considered 0.50s' tenth digit as 0, but the tenth digit is non-zero which is 5. I beleive for decimals, there is no unit digit and it begins with tenth digit. Correct me if I'm wrong.

ildude02 wrote:The answer is B. 8x will always yield a non zero tenth digit.

I see in Tatianas explanation, she considered 0.50s' tenth digit as 0, but the tenth digit is non-zero which is 5. I beleive for decimals, there is no unit digit and it begins with tenth digit. Correct me if I'm wrong.

You're 100% correct.

If 8x is an integer, and x must be between 0 and 1, then the smallest possible value of x is .125. Every possibly value has a non-zero tenths digit (which is indeed the digit directly to the right of the decimal - the "tens" digit is actually two to the LEFT of the decimal place).

If 16x is an integer, then the smallest possible value of x is .0625, which does have a tenths digit of 0. Of course, x could also be .125, with a non-zero tenths digit; hence, (1) is insufficient.

(2) is sufficient, (1) is not: choose (B).

As a quick review:

2,436.789

2 is the thousands digit
4 is the hundreds digit
3 is the tens digit
6 is the units (or ones) digit
7 is the tenths digit
8 is the hundredths digit
9 is the thousandths digit

how about 8 (.5) = 4.0 ?

@cunu,
had the same doubt...but stuart is spot on...dont look at the answer that ur getting first..u have stated that 8*0.5=4....here, 5 is in the tenths place which is nonzero......dun worry about the answer...