Larger square roots — Aptitude Question
Larger square roots: 121 : 11 :: 169 : ? Answer and worked solution on CodeKairo.
- Topic: Analogies & Classification
- Section: Logical Reasoning
- Difficulty: Easy
- Time target: 35 seconds
Question
121 : 11 :: 169 : ?
Options
- 12
- 13
- 14
- 17
Show the answer and the worked solution
Correct answer: B. 13
Worked solution
- 11 = √121.
- √169 = 13.
Answer: 13.
The idea
Memorise squares to at least 25²: 121, 144, 169, 196, 225 come up constantly in these questions.
Shortcut. A square ending in 9 has a root ending in 3 or 7, so 169 → 13 or 17, and 17² = 289 is far too big — 13.
Common trap. 12 — assuming the root rises by one from 11, though 144 (12²) lies between 121 and 169.
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