GMAT Data Sufficiency: Master the Five Choices

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.

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.

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.

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?'

Test yourself before you move on

Re-reading a note feels like learning and produces almost none. The retrieval below is what actually builds the memory, so cover the map above and answer these from memory — out loud or written down, not in your head, because "I know this" is the feeling that fails under exam pressure.

1. Without looking: what is The question, and how does it connect to Data Sufficiency logic?
2. Without looking: what is Five fixed choices, and how does it connect to Data Sufficiency logic?
3. Without looking: what is Don't solve, and how does it connect to Data Sufficiency logic?
4. Without looking: what is AD / BCE grid, and how does it connect to Data Sufficiency logic?

Anything you could not produce is the part of this note you have not learned yet — regardless of how familiar it felt while reading. Re-read only that node, then re-test the whole set. Testing the whole set matters: recalling one idea in isolation is easier than recalling it among 4 competing ones, which is the situation the exam actually puts you in.

When to come back to this note

Spacing is not a scheduling detail, it is the mechanism. Meeting this material again just as it starts to fade forces the effortful retrieval that consolidates it, which is why a note reviewed four times across three weeks outlasts the same note read four times in one evening. The built-in scheduler resurfaces these questions at widening intervals for exactly that reason — the prompt arriving when you feel you have half-forgotten is the system working, not failing.

A practical rhythm for Data Sufficiency logic: today, again tomorrow, then after three days, then after a week. If you fail a review, shorten the next interval rather than re-reading the note end to end — the failure identifies the gap precisely, and re-reading everything wastes the diagnosis.

Then apply it under pressure. Knowing a concept in isolation and using it in a timed paper are different skills, and only the second is examined. There are 90 free GMAT practice tests here covering 1,920 questions — counted from the test files, not estimated. Take a full timed GMAT mock →