Numbers


Find the smallest value of n for which 100!/20ⁿ is not divisible by 20.
a) 24
b) 25
c) 48
d) 49
e) None

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6 comments

  1. Aastha Dhiman

    A. 24

    Max. power of 5 in 100! = 24 , and we have sufficient power of 2^2 . Hence , we will have 20^24 in 100! .
    When divided by 20^24 , it will exhaust all powers of 20 in 100! . Therefore , now 100! /20^24 will not be divisible by 20 .

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