Mental Ability & Reasoning · Section 2
Practical numbers for office work: budgets, invoices, staffing and reports. No advanced mathematics.
Section 2
This section tests whether you can use numbers accurately in the kind of work an officer does every day: reading a budget, checking an invoice, sharing resources, comparing costs and reading a table. PPSC's guidebook says the maths is practical. There is no formal algebra or geometry.
What it rewards is care and a sensible method: knowing which calculation to use, keeping units and time periods straight, spotting a wrong total or two swapped digits, and recognising when the data is not enough to answer.
Question types you will meet
Topic by topic
2.1
Percentage change = (new − old) ÷ old × 100: always divide by the original figure. Use multipliers: a 20% rise is × 1.20 and a 15% fall is × 0.85. A 10% rise then a 10% cut is 1.10 × 0.90 = 0.99, a net fall of 1%.
2.2
Know allocation, budget head, expenditure, balance (allocation minus expenditure) and variance (actual minus planned). Check whether figures are monthly, quarterly or yearly, and add every cost, including delivery and tax, before comparing.
2.3
To share in a ratio: add the parts, find one part, multiply. For inverse problems think in person-days: if 6 clerks need 10 days, the job is 60 clerk-days. Round up when you must cover a demand, down when a budget limits you.
2.4
Read the title, units, rows, columns and footnotes before calculating. The percentage change of a total is not the average of the row percentages when the rows differ in size.
2.5
Total = average × count, and nearly every average problem becomes simple once you work with totals. One large figure can pull the mean up, so the median often describes the typical case better. Never average averages of different-sized groups.
2.6
"Per" means divide and "of" means multiply. Convert everything to the same unit first, and keep working days separate from calendar days. Know that 1 lakh is 100,000, 1 million is 10 lakh and 1 crore is 100 lakh.
2.7
Look for transposed digits (6358 as 6538), an extra or missing zero, wrong totals, wrong units, double counting and missing items. Check line by line, then the sum, then against the source documents.
2.8
Goal, facts, units, plan, solve, check. Some questions cannot be answered from the data: if 40% of a budget is spent you know 60% remains, but not a rupee figure without the total.
Good habits
Common traps
Try them first
Answer each question yourself, then open the explanation to check your method. The samples from PPSC's official guidebook show the real style of the test.
The procurement department bought 12 office chairs for Rs. 96,000. It now needs 5 more of the same model. The vendor gives a flat 10% discount on the unit price for any additional chairs. What is the total cost of the 5 additional chairs?
Answer: A. Rs. 36,000
Exam tip: The discount applies only to the extra chairs, so the first 12 do not affect the answer.
A department's quarterly budget was 40% on staff salaries, 35% on office operations, and the remaining Rs. 250,000 on software subscriptions. What was the amount allocated to staff salaries?
Answer: B. Rs. 400,000
Exam tip: Rs. 1,000,000 is the total budget: a trap for anyone who stops one step early.
A register shows: W: ID 4826, slip 4826. X: ID 7194, slip 7194. Y: ID 6358, slip 6538. Z: ID 2047, slip 2047. Which record has a mismatch?
Answer: C. Person Y
Exam tip: The difference between swapped-digit numbers always divides by 9 (6538 − 6358 = 180).
An office has 80 employees, and 28 of them work remotely. What percentage of employees work remotely?
Answer: D. 35%
A verification call needs one continuous 25-minute free slot. A person is unavailable from 9:40 to 10:05 and from 10:30 to 11:00. Which slot can be used?
Answer: B. 10:05 to 10:30
Exam tip: A slot can begin exactly when a busy period ends.
An office has an annual budget of Rs. 480,000. It spent Rs. 150,000 in the first quarter and Rs. 130,000 in the second. If it keeps spending at the average rate of these two quarters, what will the position be at the end of the year?
Answer: D. Rs. 80,000 overspent
Exam tip: Rs. 200,000 is only the balance today. The question asks about the year end.
A licence fee rose from Rs. 2,000 to Rs. 2,500. It was later cut by 20%. Compared with the original fee, the final fee is:
Answer: B. unchanged
Exam tip: A 25% rise and a 20% cut cancel out (1.25 × 0.80 = 1), because each percentage uses a different base.
Eight clerks can clear a backlog of files in 15 days. How long would 12 clerks take, working at the same rate?
Answer: A. 10 days
Exam tip: More clerks means fewer days: an inverse relationship, so do not scale up.
Office A has 20 staff who each process 30 files a day on average. Office B has 30 staff who average 40 files a day. What is the average for all 50 staff?
Answer: D. 36
Exam tip: 35 is the average of the two averages, which ignores that Office B is larger.
PPSC Mental Ability Test Series
Timed quizzes on this section only, with your score and every answer explained after you submit. For a quiz that mixes all four sections, see the trial quiz and full mixed tests.
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CSS Nexus Mental Ability and Reasoning Workbook (PDF)
554 pages covering all four sections: lessons, 367 solved examples, 794 practice questions with answer keys, and a timed test for each section.
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