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CSAT 2023 paper

UPSC CSE CSAT 2023 · Question 80 · Puzzles, arrangements & general mental ability

The letters of the word “INCOMPREHENSIBILITIES” are arranged alphabetically in reverse order. How…

The letters of the word “INCOMPREHENSIBILITIES” are arranged alphabetically in reverse order. How many positions of the letter/letters will remain unchanged?

Answer & explanation

Answer: (c) Two

In reverse alphabetical order the 21 letters read TSSRPONNMLIIIIIHEEECB. The five I's fill positions 11 to 15, and the original word has I at positions 13 and 15, so exactly two positions stay the same.

  1. Letters (21): I × 5, E × 3, N × 2, S × 2 and one each of B, C, H, L, M, O, P, R, T.
  2. Reverse alphabetical order: T S S R P O N N M L I I I I I H E E E C B.
  3. The I's now occupy positions 11 to 15.
  4. In INCOMPREHENSIBILITIES, I stands at positions 1, 13, 15, 17 and 19 — so positions 13 and 15 match.
  5. Check the rest one by one (1: I vs T, 11: N vs I, 16: L vs H, 20: E vs C …): no other match. Two positions stay unchanged.

Remember · For 'unchanged positions', write the new order with position numbers; check the block of the most repeated letter first — matches usually hide there.

Question and answer: UPSC's official GS Paper II (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

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