Numerical Reasoning
What the section tests
Numerical Reasoning presents tables, charts and short data scenarios and asks you to extract, compare and manipulate figures under time pressure. A calculator is rarely needed; estimation and clean arithmetic are the intended route.
Concepts you must command
- Percentage change = (new − old) ÷ old × 100; the base is whatever you change from.
- Percentage points vs. percent: a rate moving from 20% to 25% rises 5 percentage points but 25 percent.
- Successive changes do not add: +10% then −10% leaves 0.99 of the original, not 1.00.
- Ratios and proportions: scale both parts; keep part-to-part distinct from part-to-whole.
- Weighted averages: a combined average lies between the group averages, closer to the larger group.
- Rates: convert units deliberately (per month to per year, km/h to m/s).
Traps
The classic is using the wrong base - computing a rise as a fraction of the new value. Another is unit mismatch between question and table (thousands vs. millions, quarters vs. years). Irrelevant columns are included to slow you down, and multi-step questions often hide a second operation after the obvious one. In 'by what percent is A greater than B' questions the base is B, not A.
Rule of thumb
Write the formula with numbers substituted before computing, keep units attached, and sanity-check magnitude: a share cannot exceed 100%, and a 400% increase means five times the original.
Worked example: revenue falls from 80 to 60. Change = (60 − 80) ÷ 80 = −25%, not −20%, because the base is the original 80.