Master this topic with zero to advance depth.
Data Sufficiency is NOT about solving the problem. It is about checking IF the problem CAN be solved with the given data. Do not waste time calculating the final mathematical or logical answer unless absolutely necessary to verify uniqueness.
Always follow this strict flowchart to avoid the 'Merge Trap':
1. Check Statement I alone.
2. If insufficient, check Statement II ALONE (forget statement I exists!).
3. If BOTH are individually insufficient, ONLY THEN combine Statement I + II.
Never look at Statement II while evaluating Statement I on your first pass.
Mains exams use 3-statement DS (I, II, and III).
Exam Attack: Look at the answer options first! If options are 'I and II', 'II and III', 'Any two of the three', do not blindly test all 7 mathematical combinations (I, II, III, I+II, II+III, I+III, I+II+III). Let the options guide your grouping.