In a certain code if 64 is written as 343 and 216 is written as 729, then how is 512 written in that code?
Answer & explanation
Answer: (b) 1331
Both examples turn a cube n³ into (n + 3)³: 4³ becomes 7³ and 6³ becomes 9³. So 512 = 8³ becomes 11³ = 1331.
- 64 = 4³ and 343 = 7³; 216 = 6³ and 729 = 9³.
- The rule: n³ is written as (n + 3)³.
- 512 = 8³, so it is written as 11³ = 1331.
Remember · Recognise squares and cubes at sight (up to 20² and 12³); number codes often shift the base.
Question and answer: UPSC's official GS Paper II (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·