Numerical Reasoning and Quantitative Aptitude
What this domain tests
Numerical reasoning checks speed and accuracy with arithmetic, percentages, ratios, averages, rates, and data interpretation. Quantitative aptitude adds algebra, geometry, and number properties. The emphasis is on estimation and clean method, not long computation.
Concepts to master
- Percentage change: increase then decrease of the same percentage never returns to the original (a 20% rise then 20% fall leaves 96%).
- Ratio and proportion: scale to a common unit before combining ratios (A:B = 2:3, B:C = 4:5 becomes A:B:C = 8:12:15).
- Averages: total = average × count; adding a value shifts the mean by (new value − old mean)/new count.
- Rate problems: distance = speed × time; work rates add as reciprocals.
- Data interpretation: read axis labels and units before computing.
Traps to expect
- Unit mismatches - minutes against hours, grams against kilograms.
- Percentage of what? A discount applied to an already discounted price.
- Average of averages - you cannot average two group means without weighting by group size.
- Rounding too early - carry full precision and round only at the end.
- Answer options that match a common intermediate step, catching candidates who stop halfway.
Rule of thumb
Before calculating, write down the units and the target quantity. If the answer choices are widely spaced, estimate: 48 × 21 ≈ 50 × 20 = 1000, then pick the nearest option.
Worked example
A jacket costs 80 and is reduced 25%, then a further 10% off the sale price. Final price = 80 × 0.75 × 0.90 = 80 × 0.675 = 54. Note the total discount is 32.5%, not 35%, because the second discount applies to the reduced price.