Numerical Reasoning
What is measured
Short tables, charts and scenarios testing percentage change, ratios, rates, averages, currency conversion and proportional reasoning, usually with limited time and sometimes without a calculator. Accuracy in setting up the calculation matters more than raw arithmetic speed.
Traps to expect
- Percentage points versus percent. A rate rising from 5% to 8% rises 3 percentage points, but that is a 60% increase.
- Changing base. Successive percentage changes never simply add.
- "More than" versus "of". "A is 25% more than B" means A = 1.25B; "A is 25% of B" means A = 0.25B.
- Units and periods. Per-day versus per-week figures, cents versus dollars, and columns headed "thousands".
- Averages of averages. Never average group means without weighting by group size.
Worked example
A price rises 20% and later falls 20%. Adding the changes gives zero, but the multipliers give 1.20 × 0.80 = 0.96 - a net fall of 4%. Whenever a quantity changes by percentages in sequence, multiply the multipliers.
Rule of thumb
Convert every figure to a common unit, write the formula in words before touching numbers, then estimate the answer first so you can spot a misplaced decimal.