Numerical Reasoning - Correct Setup, Fast Estimation
The numerical module tests quantitative reasoning rather than arithmetic drill: tables, charts and short scenarios involving percentages, ratios, averages, growth, unit conversion and cost, plus number series. A calculator is usually not allowed and time per item is short, so marks come from setting up the calculation correctly and estimating fast.
Find the base before you compute
Every percentage has a base. 'Up 12%' means 12% of the earlier figure; a change from 20% to 25% is 5 percentage points but a 25% relative increase (5/20). Two successive changes do not cancel: +10% then −10% leaves 99% of the original. 'How much more than' means subtract; 'how many times more' means divide.
Estimate, then calculate exactly
Round to one significant figure to locate the answer among the options and to catch a factor-of-ten slip. In tables, read the row and column labels, the units (thousands, millions, euro or dollar) and any axis break. Check whether figures are totals or averages; never average percentages without weighting by their bases.
Worked example
'A service handled 8,400 files in 2023 and 9,240 in 2024. The 2025 target is 5% above the 2024 figure. How many files is the target?' Growth 2023 to 2024: 9,240 − 8,400 = 840; 840/8,400 = 0.10, i.e. +10%. Target: 9,240 × 1.05 = 9,702. A distractor of 9,450 comes from applying 5% to 2023; 9,245 comes from adding percentage points. Write the base under each percentage before touching the keypad.
Series items
Take first differences (6, 11, 18 gives +5, +7); if they are not constant, take second differences; check ratios for geometric series; check alternating series where odd and even positions follow separate rules; look for squares, primes and n squared plus or minus one.
Traps that cost marks
- Percentage of the wrong base, the most common single error.
- Averaging averages instead of computing a weighted mean.
- Mixing units: minutes with hours, thousands with units, net with gross.
- Rounding mid-calculation, then rounding again.
- Answering the wrong question: total instead of difference, per month instead of per year.
- Burning time on one item: if the setup is not clear in about a minute, flag it and move on.