GATE 2025 Chemical Engineering, Q3 · Mathematics
The correct answer is C, e − 1.
Question
The sum of the following infinite series is: 1/1! + 1/2! + 1/3! + 1/4! + 1/5! + ⋯
Official answer: e − 1
Why
GATE 2025 official key: (C). Since e = 1 + 1/1! + 1/2! + 1/3! + ⋯, the given series (which omits the leading 1) sums to e − 1.
Explanation cross-checked for consistency. Final answer matches the official IIT answer key.