Next CSE-PPT: 14 March 2027 · Professional & Subprofessional
Civil Service Exam numerical ability reviewer on age problems (past, present and future ages, ratios and averages) and number problems (digits, consecutive numbers, sums, remainders, GCF and LCM).
Age problems compare ages at different times; the key fact is that everyone grows older by the same number of years. Number problems ask about digits, consecutive numbers, sums, products and remainders. For both, define one unknown, write an equation from the words, solve it and check the answer against every condition.
Every answer in this set was calculated and checked by script. Calculators are not allowed in the Civil Service Exam, so practise each item on paper and look for the shortcut shown in the explanation.
Correct answer: A. 12 years old
Let the son be s and the father 3s. Then 4s = 48, so s = 12 and the father is 36. Check: 36 = 3 × 12 and 12 + 36 = 48. The "parts" method gives the same result: 1 part + 3 parts = 4 parts = 48.
Read detailsCorrect answer: A. 10 years old
In 5 years Ana will be 30, so Ben will be 15 then and is 10 now. The option 12.5 comes from halving Ana's present age, which ignores the 5 years.
Read detailsCorrect answer: D. 14 years old
Six years ago the mother was 32, so the daughter was 8 then. Now the daughter is 8 + 6 = 14. Remember to add the years back after solving for the past age.
Read detailsCorrect answer: D. 40 years old
There are 3 + 5 = 8 parts, each worth 64 ÷ 8 = 8 years. The older sibling has 5 parts: 40 years. The younger is 24. Check: 24 + 40 = 64 and 24 : 40 simplifies to 3 : 5.
Read detailsCorrect answer: D. 40 years old
The total age of the first four is 4 × 30 = 120. The new total is 5 × 32 = 160. The new member is 160 − 120 = 40 years old.
Read detailsCorrect answer: D. 63
If the ones digit is d, the tens digit is 2d and 3d = 9, so d = 3. The number is 63. Note that 36 has the digits reversed.
Read detailsCorrect answer: B. 14
Write 2n + 9 = 37. Subtract 9: 2n = 28, so n = 14. Check: 2 × 14 + 9 = 37. Translate each phrase in order: "twice a number" is 2n, and "increased by 9" adds 9. The option 23 comes from subtracting 9 from 37 and stopping there, without halving.
Read detailsCorrect answer: D. 27
The middle number is 75 ÷ 3 = 25, so the numbers are 23, 25 and 27. The largest is 27. Consecutive odd numbers differ by 2.
Read detailsCorrect answer: B. 1,275
Use the formula n(n + 1) ÷ 2 = 50 × 51 ÷ 2 = 1,275. It works because the numbers pair up: 1 + 50, 2 + 49 and so on give 25 pairs of 51.
Read detailsCorrect answer: B. 12
Since 12 × 12 = 144 and 13 × 13 = 169, the numbers lie around 12 and 13. Check: 12 × 13 = 156, so the smaller number is 12.
Read detailsCorrect answer: A. 10/13
Let the denominator be d and the numerator d − 3. Then (d − 1)/(d + 2) = 4/5, so 5d − 5 = 4d + 8 and d = 13. The fraction is 10/13. Check: 12/15 = 4/5.
Read detailsCorrect answer: C. 2
Test the options: 2 + 1/2 = 2.5. The other choices give 2, about 2.17 and about 3.33. (The number 1/2 also works, since 1/2 + 2 = 2.5.)
Read detailsCorrect answer: C. 61
The LCM of 2, 3, 4, 5 and 6 is 60, so the number is 60 + 1 = 61. 121 also works but is larger, while 31 and 59 fail (31 ÷ 4 leaves 3, and 59 ÷ 3 leaves 2).
Read detailsCorrect answer: A. 20 years
Solve 70 + x = 3(10 + x): 70 + x = 30 + 3x, so 40 = 2x and x = 20. Check: in 20 years Lolo will be 90 and the grandson 30.
Read detailsCorrect answer: D. 18 years old
Two-thirds of 27: 27 ÷ 3 = 9, and 9 × 2 = 18. The option 9 is only one-third of Ben's age. "Two-thirds of" means multiply by 2/3. Check: 18 ÷ 27 = 2/3.
Read detailsCorrect answer: B. 11 years old
In 10 years, Lito will be L + 10 and Rosa L + 18. Then 2L + 28 = 50, so L = 11. Rosa is now 19. Note that 19 is Rosa's age, not Lito's.
Read detailsCorrect answer: A. 12
Factors of 36 include 1, 2, 3, 4, 6, 9, 12, 18 and 36; factors of 48 include 12 but not 18 or 36. The greatest common one is 12. With primes: 36 = 2² × 3² and 48 = 2⁴ × 3, so GCF = 2² × 3 = 12.
Read detailsCorrect answer: A. 49
There are 12 parts in all, each worth 84 ÷ 12 = 7. The larger part is 7 × 7 = 49 and the smaller is 35. Check: 35 + 49 = 84.
Read detailsCorrect answer: A. 23
The three numbers must add up to 3 × 20 = 60. The third is 60 − 15 − 22 = 23. Check: (15 + 22 + 23) ÷ 3 = 60 ÷ 3 = 20. Whenever an average is given, convert it into a total first by multiplying by the number of items.
Read detailsCorrect answer: C. 67
Number = divisor × quotient + remainder = 7 × 9 + 4 = 67. Check: 67 ÷ 7 = 9 remainder 4. The remainder must always be smaller than the divisor, so a remainder of 4 with a divisor of 7 is valid.
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