Solved UPSC CDS/OTA Question
A solved UPSC CDS/OTA PYQ — decoded step-by-step.
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Q · Number systemHard · 45s
Find the sum of the first 20 even numbers.
TopicNumber system
Question Typemultiple choice
DifficultyHard
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained — no skipped algebra.
Solve step-by-step using number system concepts. Find the sum of the first 20 even numbers. → 420
Final Answer: Option C — 420