Numerical Reasoning
What the section tests
Numerical reasoning for clerical roles is practical arithmetic applied to work-like data: percentages, ratios and proportions, averages, money, unit conversions, timetables, and reading tables or simple charts. Speed matters, but accuracy matters more - one misplaced decimal is a wrong answer.
Core skills to drill
- Percentages: finding a part, a whole, and a percentage change. Of means multiply; per cent means ÷100.
- Averages: mean = total ÷ count. Be ready to work backwards from a mean to a missing value.
- Ratios: convert to parts, find the value of one part, then scale up.
- Time: keep minutes as minutes and convert only when asked (45 minutes = 0.75 hours, not 0.45).
- Estimation: round first to predict the answer’s size, then compute precisely.
Recurring traps
- Percentage change versus percentage points; a 10% rise then a 10% fall does not return to the starting figure.
- Dividing by the wrong total - e.g. the number of rows rather than the number of items.
- Unit mismatch: pence versus pounds, minutes versus hours, grams versus kilograms.
- Rounding too early and losing the exact answer.
- Reading the adjacent column of a table under time pressure.
Worked example
A team processes 240 files and 15% are rejected. How many are accepted?
Rejected = 240 × 0.15 = 36. Accepted = 240 − 36 = 204. Shortcut: 240 × 0.85 = 204.
Rule of thumb
Estimate, calculate, then sanity-check size and units. 204 passes a quick “about 200” test; 2,040 or 20.4 would not.