Hey Nona,

You're in the same position as quite a few test-takers...the level that most test-takers get to is "comfortable with math / comfortable with the AD...BCE answer choice setup". But the next level is where Data Sufficiency is really played.

Data Sufficiency is not simply a strange way to ask a math problem.

What Data Sufficiency is is a logic puzzle / strategy game that requires an understanding of math. In a way it's a lot like poker - some of the best players don't play the cards (the math in DS) as much as they play the opponents. In Data Sufficiency, that means looking at clues. For example, if one statement is obviously not sufficient - if there's no way a C student in junior high would ever say it's sufficient - you have to see it as a clue that there's a larger game being played, that there's a reason that statement exists.

Consider the example:

Is a/b > 5?

(1) a > 5b
(2) b > 0

There's absolutely no way you should ever think that statement 2 is sufficient. It only tells you about b and puts no limits on a. So why is it there? To save you from a bad decision on statement 1, which in a vacuum most test-takers would say is sufficient. If you simply divided both sides by b with statement 1, turning "a > 5b" into "a/b > 5" and a definite "yes", statement 2 is there to give you a clue. "Why does it matter that b is positive?" - if you ask yourself that, you should recognize that if b were negative, statement 1 would then read "a/b < 5" (you have to flip the sign when dividing by a negative), so statement 1 is actually NOT sufficient. You need that piece of information from statement 2, so the answer is C.

Now, in this case that clue in statement 2 is pretty clear as it reads directly "b is positive". In a harder question, it might read (2) b > 3 or something like that - the same clue, but hidden a little since >0 literally means "positive" whereas >3 makes you infer "positive".

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This is just one example, but the larger point is that Data Sufficiency requires strategic thinking and paying attention to clues within the question. It's not just about the math, and once questions get harder there's usually more of that strategy involved than people realize. Here are a few videos and posts that cover that kind of strategy:

https://www.youtube.com/watch?v=S0dGbUb7X88

https://www.youtube.com/watch?v=Rlos1WQJMaQ

https://www.veritasprep.com/blog/2013/03 ... rift-shop/

https://www.veritasprep.com/blog/2012/09 ... fficiency/

https://www.veritasprep.com/blog/2012/02 ... s-success/