WHAT YOU NEED TO KNOW
Current GMAT Quantitative Reasoning focuses on arithmetic and algebra problem solving. Data Sufficiency belongs to Data Insights, so separate the two when choosing practice material.
Match practice to the section
GMAC’s current content page places Problem Solving in Quantitative Reasoning and Data Sufficiency in Data Insights. A calculator is not available in Quantitative Reasoning; Data Insights has an on-screen calculator. The old article’s mixed quantitative section and universal calculator ban were misleading.
Start with fractions, percentages, ratios, equations and translating words into relationships. Check the current syllabus before spending preparation time on a topic simply because it appears in an older book.
Solve a percentage change carefully
Original example: a price rises by 20% and then falls by 20%. Starting from 100, the increase gives 120. The decrease is 20% of 120, or 24, leaving 96. The final value is 4% below the start, not unchanged.
The error comes from using the same base for both percentages. Write the base beside each operation. A quick estimate or a convenient starting value can help check the reasoning, provided the question permits that substitution.
Test assumptions before calculating
Identify what the question actually asks and which quantities are constrained. Do not assume that a variable is positive, a whole number or a monetary amount unless the information establishes it. A neat calculation can still answer the wrong question.
For Data Sufficiency practice, distinguish finding a value from deciding whether the information determines one. For example, x squared equals 9 does not identify x uniquely unless another condition excludes either 3 or −3. This illustrates reasoning, not an official exam item.
Build speed after accuracy
Explain a method without looking at the solution, then practise a short set under time. Mark whether an error came from interpretation, algebra, arithmetic or an unsupported assumption. Target the repeated cause.
Your next action is to redo three missed problems and write one sentence naming the assumption or operation that failed. Follow them with fresh examples. Do not use a calculator during practice that is intended to simulate the Quantitative section.
Sources and further reading
Sources checked 2026-10-13. Examples and planning suggestions are Effikos editorial guidance.
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