stmt2,

s=4

r/s=r*1/4

=r*0.25

Whatever values of r, the result is decimal with finite number of integers.

So B is sufficient.

whenever a odd number is divided by 2^n,it result in decimal with finite number of integers.

Great explanation, Selango - if I can just tack on a little bit, this is one case in which it may be particularly helpful to be able to think of division problems in a few ways.

Let's consider the possibility of 11 divided by 4. We could express that as:

11/4 (a fraction)

2 and 1/4 (a mixed number, in which we'll take the number of times that 4 goes in evenly to 11, and then take what's left and divide back by 4 as a fraction)

2 remainder 1 (much like the mixed number but we leave the remainder as is and don't divide it back in)

2.25 (we take the mixed number and actually calculate it to a decimal place)


The GMAT likes to test your flexibility with these ways of expressing division, and this problem is a good example. r/s, if s = 4, is r/4. With that, to find the decimal we'd take whatever the remainder is and divide it back by 4. Those possibilities are:

No remainder --> Nothing after the decimal place.
Remainder 1 --> 1/4 ---> .25
Remainder 2 --> 1/2 ----> .5
Remainder 3 --> 3/4 ---> .75

Had they asked about a different value of s, we could try the same thing until we either found a repeating and a terminal decimal or recognized that we wouldn't. Say that s were 6, we'd have:

Remainder 1 ---> 1/6 ---> .166666......
Remainder 2 ---> 2/6 ---> 1/3 ---> .333333..........
Remainder 3 ----> 3/6 ---> 1/2 ----> .5

Now we have both a terminal decimal (.5) and a repeating decimal (.16666...), so this one wouldn't be sufficient.



I'd say that this question is much more about your ability to recognize the concept behind division than it is about knowing particular rules for numbers - once you know the concept the trial-and-error for the division shouldn't be that time-consuming or difficult, but the real catch is recognizing that if they're asking about division in a more conceptual framework you should be thinking about that relationship between remainder, fraction, and decimal.