Solved UPSC CDS/OTA Question
A solved UPSC CDS/OTA PYQ — decoded step-by-step.
Solve it the standard way once — then learn the shortcut.
Q · LogarithmMedium · 45s
If log₂ = .301, find the number of digits in (125)25.
TopicLogarithm
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained — no skipped algebra.
logy = 25 log₁₂₅
= 25[log₁₀₀₀ – 3log₂] = 25 × (2.097) = 52 +
Hence 53 digits
Final Answer: Option B — 50