UPSC Prelims 2026 CSAT, question 45

Solution.

Answer: (c) 3

1. The powers of $2$ around the three-digit range ($100$ to $999$) are $2^6 = 64$, $2^7 = 128$, $2^8 = 256$, $2^9 = 512$, and $2^{10} = 1024$.
2. Exactly three of these ($128, 256,$ and $512$) are three-digit numbers.