What is your task in a Data Sufficiency question?

To judge whether the statements provide enough information to answer — not to solve for the value.

What do the five Data Sufficiency answer choices represent?

Statement 1 alone, statement 2 alone, both together, either alone, or neither is sufficient.

Why must you test each statement alone before combining them?

Combining too early makes insufficient statements look sufficient by smuggling in the other statement.

What does the AD/BCE grid do?

If statement 1 is sufficient the answer is A or D; if not, it's B, C or E — narrowing five choices to a couple.

What's a common 'looks sufficient' trap?

A statement that leaves two possible values, such as x² = 16 giving x = 4 or −4, which is not sufficient.

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GMAT Data Sufficiency: Master the Five Choices

The GMAT's most misunderstood question — a deep dive into judging sufficiency instead of solving, with the AD/BCE shortcut.

The big picture

Data Sufficiency logic
- The question — Statements 1 & 2 — is each enough?
- Five fixed choices — 1, 2, both, either, or neither
- Don't solve — Judge sufficiency, stop there
- AD / BCE grid — Eliminate systematically

You judge sufficiency, you don't solve

A Data Sufficiency item gives a question and two statements. Your job is to decide whether the information is enough to answer — not to produce the number. The five answer choices never change, so memorise them: (A) statement 1 alone, (B) statement 2 alone, (C) both together, (D) either alone, (E) neither.

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Real example: 'What is x?' If statement 1 says 'x is even' and statement 2 says 'x = 4', you don't care that x is 4 for its own sake — you note that statement 2 alone pins it down, so the answer is (B).

🧠 Memory hook: The question is 'ENOUGH?', never 'what's the value?'. Five choices, memorised cold.

Test each statement alone, first

Always evaluate statement 1 by itself, then statement 2 by itself, before combining. Combining too early is the classic error — it makes insufficient statements look sufficient because you've smuggled in the other one.

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Real example: If statement 1 alone answers it AND statement 2 alone answers it, the answer is (D) 'either alone' — you'd miss that if you jumped straight to combining them.

🧠 Memory hook: One at a time BEFORE together. Combining early fakes sufficiency.

Use the AD / BCE elimination grid

A fast framework: if statement 1 is sufficient, the answer is A or D (cross off B, C, E). If statement 1 is not sufficient, it's B, C or E (cross off A and D). Then test statement 2 to finish. This turns five options into two or three quickly.

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Real example: Statement 1 works → you're in 'AD'. Now check statement 2: if it also works alone, it's D; if not, it's A. Two clean decisions instead of juggling five options.

🧠 Memory hook: Statement 1 works → AD. Doesn't → BCE. Then check statement 2.

Beware the 'looks sufficient' trap

A statement can seem to pin down an answer but leave two possibilities — often a positive/negative or an integer/fraction case. Before calling something sufficient, ask 'could there be another value that also fits?'

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Real example: 'x² = 16' feels sufficient for 'what is x?' but x could be 4 OR −4 — two values, so it's NOT sufficient. Always test whether a second case sneaks in.

🧠 Memory hook: Before you say 'sufficient', hunt a second value (±, integer vs fraction).

Frequently asked questions

What is your task in a Data Sufficiency question?: To judge whether the statements provide enough information to answer — not to solve for the value.
What do the five Data Sufficiency answer choices represent?: Statement 1 alone, statement 2 alone, both together, either alone, or neither is sufficient.
Why must you test each statement alone before combining them?: Combining too early makes insufficient statements look sufficient by smuggling in the other statement.
What does the AD/BCE grid do?: If statement 1 is sufficient the answer is A or D; if not, it's B, C or E — narrowing five choices to a couple.
What's a common 'looks sufficient' trap?: A statement that leaves two possible values, such as x² = 16 giving x = 4 or −4, which is not sufficient.

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