Erudex journal
Numerical Reasoning Practice Test: Percentages, Ratios and Tables
A correct numerical answer starts with choosing the right denominator and reading the units. These five original examples practise common arithmetic skills alongside the Erudex numerical reasoning papers. They are learning examples, not questions from an employer's assessment.
Attempt the questions without reading the answers first. A calculator may be useful for checking, but follow the instructions of any actual test you take. Erudex's linked fixed practice papers contain ten questions each and explanations after submission; repeated-paper improvements can reflect familiarity.
Key points
- •Use the starting value for percentage change.
- •Divide by the remaining proportion for reverse percentages.
- •Compare rates when group sizes differ.
- •Weight averages by the number of observations.
1. Percentage increase
Sales rise from 80 units to 100. What is the percentage increase? The change is 20 and the original value is 80, so 20/80×100 = 25%. Dividing by 100 instead gives 20%, which answers a different comparison.
To check, increase 80 by 25%: 80×1.25 = 100. The direction matters. A fall from 100 to 80 is 20%, not 25%, because the starting value changed.
2. Reverse percentage
An item costs 72 after a 10% discount. What was the original price? The discounted price is 90% of the original. Divide 72 by 0.9 to obtain 80. Adding 10% of 72 gives 79.2, not the original price.
Write the equation 0.9×original = 72 before calculating. Reapply the discount to check: 80×0.9 = 72. Currency units do not change the arithmetic, but round only when the problem requires it.
3. Divide a total using a ratio
A team of 48 has analysts and engineers in a ratio of 3:5. The ratio has eight parts; each part contains 48/8 = 6 people. There are 18 analysts and 30 engineers.
Check both the total and the ratio. Treating 3:5 as 3/5 of all staff gives the wrong analyst count because 5 is one group's parts, not the total number of parts.
4. Compare rates in a small table
Branch A receives 200 enquiries and closes 30 sales. Branch B receives 120 enquiries and closes 24 sales. Which has the better conversion rate? A converts 30/200 = 15%; B converts 24/120 = 20%. A has more sales, but B has the higher rate.
Do not compare raw totals when the question asks for a rate. The denominator is enquiries, not sales. These invented figures cannot explain why one branch performs differently; they only support the requested comparison.
Branch | Enquiries | Sales
A | 200 | 30
B | 120 | 245. Calculate a weighted average
Ten products cost 4 each and thirty products cost 6 each. What is the average cost per product? Total cost is 10×4 + 30×6 = 220; total count is 40. The weighted average is 220/40 = 5.5.
The simple average of the two prices is 5, but it gives each group equal weight despite different quantities. A sensible answer should lie between 4 and 6 and closer to 6 because most products cost 6.
Review before adding a timer
For every missed answer, name the error: incorrect base, inverted ratio, wrong unit, arithmetic or unsupported inference. Solve one changed example and explain the check you used. A guessed correct answer still needs review.
Then try a linked numerical paper and review its explanations. Keep a note of first-attempt accuracy separately from repeat attempts. Employers should interpret screening results alongside job-relevant evidence, accessibility needs and structured interviews, not as a sole hiring decision or validated prediction of performance.
Frequently asked questions
- Is a numerical reasoning test the same as an IQ test?
- No. This practice focuses on numerical tasks. It does not establish a clinical IQ score or a validated overall ability measure.
- Should I prioritise speed or accuracy?
- First establish a reliable method and unit checks, then practise within the actual paper's time limit. Avoid counting memorised repeat answers as independent improvement.