GMAT Math Data Sufficiency

Data sufficiency questions consist of a question followed by two statements. Your job is to decide whether the information in the statements (taken singly or together) is sufficient to answer the question.

These questions require much less calculation than standard problem solving: evaluate rather than calculate.

How to approach data sufficiency questions

  1. learn the answer choices before doing practice questions
  2. read the question and make any deductions from the data
  3. think about what you need to solve the question
  4. consider the statements one at a time
  5. do not actually solve the problem

Practice the minitests and study the explanations for the ones you get wrong. The explanations will make the method clearer.

Each test has ten questions and should take 12 minutes.

Remember that variables (x, y etc.) can be positive, negative, zero or fractions, unless the question states otherwise.


Each problem consists of a problem followed by two statements. Decide whether the data in the statements are sufficient to answer the question. Select your answer according to whether:

  • (A) statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question
  • (B) statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question
  • (C) both statements taken together are sufficient to answer the question, but neither statement alone is sufficient
  • (D) each statement alone is sufficient
  • (E) statements 1 and 2 together are not sufficient, and additional data is needed to answer the question

Sample question

What is the value of x?

  1. the square of x is 36
  2. x(x-6) = 0


From statement 1, x = 6 or -6
From statement 2, x = 0 or 6
The answer is C because when the information from both statements is taken together x = 6

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