GMAT Data Sufficiency
Data sufficiency questions — test each statement before you solve
Data sufficiency questions ask whether two numbered statements, alone or together, settle the question. A value question needs one uniquely determined value; a yes-or-no question needs the same answer in every allowed case. A definite no is sufficient. Test each statement independently before combining them, and respect the stated domain. On the GMAT, this format belongs to Data Insights. Quant Daily offers original supplementary practice, not official exam questions.
The five choices are fixed. Statement (1) alone, statement (2) alone, both together, each alone, or neither. A value question is sufficient only when one number survives. A yes-or-no question is sufficient when every remaining integer gives the same answer, yes or no. Not affiliated with ETS or GMAC.
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This format is on GMAT Practice, not GRE Practice. The drill link opens it on the GMAT track. If you already chose GRE, switch to GMAT in Settings. The shared daily does not include it. Not affiliated with ETS or GMAC.
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How to solve data sufficiency questions by testing each statement
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Read the question type first
A value question needs one uniquely determined value. A yes-or-no question needs the same answer for every allowed case; a definite no counts just as much as a definite yes.
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Test statement (1) on its own
Ignore statement (2). For a value question, check whether one value remains in the printed domain. For a yes-or-no question, check whether all allowed cases give the same answer, even if several values remain.
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Test statement (2) the same way
Start again from the original domain and question, without carrying over statement (1). Judge whether this statement alone fixes the requested value or yes-or-no answer.
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Combine them only if each one failed
Choose C when neither statement settles the question alone but together they do. For a value question, the pair must fix one value. For a yes-or-no question, the pair must give one definite answer; multiple values can still be sufficient.
What each letter means
| Letter | When it is the answer |
|---|
| A | Statement (1) alone is enough, and (2) is not |
| B | Statement (2) alone is enough, and (1) is not |
| C | Only the two statements together are enough |
| D | Each statement alone is enough |
| E | Even together, more than one answer remains |
Can a definite no be sufficient?
On the current GMAT, Data Sufficiency belongs to Data Insights, separate from Quantitative Reasoning. See GMAC’s question-format guide.
Original worked example: n is a positive integer. Is n even?
(1) n = 2k + 1, where k is an integer.
(2) n is prime.
- Statement (1) alone makes n odd. The answer is always no, so it is sufficient.
- Statement (2) alone permits n = 2 (even) and n = 3 (odd). Both answers are possible, so it is insufficient.
Answer A: (1) alone is sufficient, but (2) alone is not. Several odd values can satisfy (1); that does not matter because the requested yes-or-no answer stays fixed.
Find matching topics in GMAT quant and Data Sufficiency practice. This is supplementary practice, not an official question or a complete exam course.
3 sample data sufficiency questions, with worked solutions
Generated by the same engine that mints the Quant Daily daily. Each answer is computed
from the numbers printed in the question, and the walkthrough below each one is the engine's own working
— not a solution written afterwards. Reload this page's live drill and you get different numbers.
Question 1
x is an integer from −11 to 11.
(1) x³ = 125.
(2) |x| = 5.
What is the value of x?
- Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
- Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
- BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
- EACH statement ALONE is sufficient.
- Statements (1) and (2) TOGETHER are NOT sufficient.
Show the worked solution
- x is an integer from −11 to 11. Those 23 cases do not all give the same answer (−11, −10, −9), so the question is still open.
- Statement (1) alone leaves 1 case, and every one answers 5, so it is sufficient.
- Statement (2) alone leaves 2 cases with more than one answer (−5, 5), so it is not sufficient.
- Both statements together leave 1 case, and every one answers 5, so it is sufficient.
- Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Question 2
x is an integer from 1 to 48.
(1) x divided by 24 leaves a remainder of 0.
(2) x is divisible by 2.
What is the remainder when x is divided by 12?
- Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
- Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
- BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
- EACH statement ALONE is sufficient.
- Statements (1) and (2) TOGETHER are NOT sufficient.
Show the worked solution
- x is an integer from 1 to 48. Those 48 cases do not all give the same answer (0, 1, 2), so the question is still open.
- Statement (1) alone leaves 2 cases, and every one answers 0, so it is sufficient.
- Statement (2) alone leaves 24 cases with more than one answer (0, 2, 4), so it is not sufficient.
- Both statements together leave 2 cases, and every one answers 0, so it is sufficient.
- Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Question 3
x is an integer from 1 to 34.
(1) x divided by 12 leaves a remainder of 7.
(2) x divided by 8 leaves a remainder of 7.
What is the remainder when x is divided by 24?
- Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
- Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
- BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
- EACH statement ALONE is sufficient.
- Statements (1) and (2) TOGETHER are NOT sufficient.
Show the worked solution
- x is an integer from 1 to 34. Those 34 cases do not all give the same answer (0, 1, 2), so the question is still open.
- Statement (1) alone leaves 3 cases with more than one answer (7, 19), so it is not sufficient.
- Statement (2) alone leaves 4 cases with more than one answer (7, 15, 23), so it is not sufficient.
- Both statements together leave 2 cases, and every one answers 7, so it is sufficient.
- Answer: BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
Common mistakes this drill is built from
The wrong options are not random numbers. Each one is the result of a specific careless error for this
topic, so picking one tells you which habit is costing you marks.
Solving for the number before judging sufficiency
The letter is the pattern of the four results, not the value of x. Finding x and then picking a value that is not among the choices wastes the clock.
Treating a yes-or-no as insufficient because the answer is no
Sufficient means every remaining integer agrees. All no is as decisive as all yes.
Ignoring the printed domain
Test only permitted values. An out-of-range or non-integer counterexample does not establish insufficiency when the question restricts you to a bounded integer domain.
Why your answer came out wrong
The specific wrong numbers this topic produces, and what each one tells you about the step
you took. If you have just got a question wrong and want to know which habit did it, start here.
Statement (1) gives two values and statement (2) gives one of them — is the answer C?
For a value question, statement (2) already settled it alone, so the answer is B. C requires each statement to fail alone and the pair to succeed. For a yes-or-no question, first check whether the two values from (1) give the same answer; if they do, (1) may also be sufficient.
Both statements say x is even. Is that enough together?
Two copies of one fact are still one fact. If even numbers in the domain do not all give the same answer, the statements together are not sufficient, and the letter is E.
FAQ
Do I have to find the value of x?
For a value question, decide whether one value remains. For a yes-or-no question, decide whether every allowed value gives the same answer. If statement (1) is sufficient, test (2) independently to distinguish A from D; do not stop before that second test.
Where does Quant Daily serve data sufficiency questions?
On GMAT Practice, at 90, 105 and 120 seconds. GRE Practice does not include this kind, and the shared daily does not either. Switch to GMAT in Settings. Not affiliated with ETS or GMAC.
What does the printed range of integers do?
It is the whole domain. A statement is sufficient only for integers inside that range. A root that sits outside the range does not count, and a root the range clips can change the letter.
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