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The remainder when \(1! + 2! + 3! + ... + 95!\) is divided by \(15\) is

Question and options

The remainder when 1!+2!+3!+...+95!1! + 2! + 3! + ... + 95! is divided by 1515 is
  1. 0
  2. 12
  3. 3
  4. 9

Answer and explanation

Correct answer: C - 3

The remainder is 33. Every factorial beginning with 5!5! contains factors 33 and 55, so the remainder comes from 1!+2!+3!+4!=33=2⋅15+31!+2!+3!+4!=33=2\cdot15+3. A remainder of 99 omits 4!4!, even though 2424 contributes to the remainder.

Practice for these exams

  • IPMAT Indore

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