UPSC Prelims 2026 · CSAT Paper 2 · Set DMathematicsQ 25 / 80

UPSC Prelims 2026 CSAT Paper 2 — Question 25

Question

How many three-digit numbers can be expressed as an integral power of 2?

(a)1
(b)2
(c)3
(d)4

UnlockIAS answer: (c)3

Solution

2⁷ = 128, 2⁸ = 256 and 2⁹ = 512 are the only powers of 2 between 100 and 999 (2⁶ = 64 is two-digit, 2¹⁰ = 1024 is four-digit). So there are 3.

UnlockIAS expert key, prepared 24 May 2026 and cross-verified by re-deriving the answer — this is our key. The official UPSC provisional key has been released.

Section

Mathematics

Topic Reference

Numeracy — Powers of 2

Official UPSC Provisional Key Released

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