# The Two Most Common Errors in Data Sufficiency

- Sep 29, 12:00 PM Comments [0]

GMAT data sufficiency questions test your ability to analyze a quantitative problem and recognize which information is necessary to figure out the solution. What a data sufficiency question does NOT test you on is your ability to calculate and number-crunch. A simpler way of addressing this might be to ask yourself a question as you work through a data sufficiency problem: “Is this enough?” Keep this in mind as you evaluate (and on test day, avoid) two specific common errors that test-takers make while taking the GMAT:

Mistake #1: Combining statements when unnecessary

This is done when a test-taker looks at both statements and says “Yes, if I have both pieces of information, then I can figure out the answer, so together the statements are sufficient.” However, you must remember that you’re also asked if either statement ALONE is enough to answer the question. Understanding the differences among all five answer choices in itself can be a boost to your quantitative score. As you look at each individual statement, ask yourself, “is this enough?” Once you can definitively answer yes or no, you are then closer to an answer to the data sufficiency problem.

Mistake #2: Over-calculating

Since you may not need to calculate an actual value for a data sufficiency question, you should avoid going into the calculation step unless absolutely necessary. For example, if dealing with a statement like:

$2x + 15 - 7x + 32 = -1$

Instead of trying to plow through with the calculations as you might have to do in a problem-solving question, recognize that you have one variable in this equation (x), and that this is solvable. So if this shows up in a data sufficiency question, the answer to the question “is this enough?” is yes, and again you are closer to solving your data sufficiency question.

Though data sufficiency questions look very abstract, there’s a hidden beauty involved in solving them. Practice these while taking on the mindset of “is this enough?” to maximize your time-management ability for the GMAT.

Arthur Ahn
Kaplan GMAT