Chemegate

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! +

  • A. ππ
  • B. 1 + e
  • C. e 1
  • D. e

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.