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Topic

Divisibility

Asked 3 times across 2 UPSC exams over 5 years (2020–2025), peaking in 2020.
3
PYQs
2
Exams
3
Years active
2020–2025
Span
2020
Peak
3/3
Answers
📅 Full chronological timeline →

Key insights

  • Most tested in CISF — 2 of 3 PYQs
  • Most asked in 2020
  • Recurs across 3 years (2020–2025)

How it travelled across exams

First appearance in each exam — the same idea, reframed.
EPFO 2020 CISF 2023

How the concept evolved

120
123
125
Rising — more than half its appearances (3 of 3) are since 2016.

Sample questions

You've seen the pattern — here are a few of the actual PYQs.
CISF2025
If for some positive integer k, 5^43 + 5^k is divisible by 7, then which one of the following could be the value of k ?
  1. A 42
  2. B 44
  3. C 46 ✓
  4. D 48
✓ Correct answer: (C)
Quantitative Aptitude › Number System
CISF2023
What is the smallest number, which when multiplied by 9 gives the product having the digit 5 only in all places?
  1. A 95283955
  2. B 61728395 ✓
  3. C 12345675
  4. D 59382716
✓ Correct answer: (B)
Quantitative Aptitude › Number System
EPFO2020
How many times does the digit 3 appear between 1 and 100 such that the number where 3 appears is not divisible by 3 ?
  1. A 11
  2. B 12 ✓
  3. C 13
  4. D 17
✓ Correct answer: (B)
Quantitative Aptitude › Number System

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