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
