UPSC CSE 2025 · PYQ · Number System / Squares · easy
If N² = 12345678987654321, then how many digits does the number N have?
A.8
B.9✓ Correct
C.10
D.11
Explanation
The number 12345678987654321 is the well-known square of 111111111 (nine 1s). Specifically, (111111111)² = 12345678987654321. Therefore N = 111111111, which has 9 digits.
💡 Practice unlimited UPSC CSE PYQs + AI-tracked progress on each topic. Sign up free →
Want more UPSC CSE practice?
Free daily 10-Q quiz · adaptive mocks · 4,000+ verified PYQs · AI doubt solver in Hindi + English