How many three-digit numbers can be expressed as an integral power of 2?
Answer & explanation
Answer: (c) 3
Powers of 2 run 64, 128, 256, 512, 1024. Only 2⁷, 2⁸ and 2⁹ — 128, 256 and 512 — have three digits.
- 2⁶ = 64 (two digits), 2⁷ = 128, 2⁸ = 256, 2⁹ = 512, 2¹⁰ = 1024 (four digits).
- Three-digit powers of 2: 128, 256, 512 — that is 3.
Remember · Know powers of 2 up to 2¹⁰ = 1024 by heart; they settle many CSAT items instantly.
Question and answer: UPSC's provisional GS Paper II (2026, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·