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Quickie XI (Posted on 2017-11-27) Difficulty: 1 of 5
What is the last digit in S=sum(n=1 to 99) n!

  Submitted by Ady TZIDON    
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Solution: (Hide)
Answer:3
Only the 1st four matter:(1+2+6+24) MOD10=3;
from n=5 on all factorials have 0 as the last digit.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionPuzzle SolutionK Sengupta2022-01-28 08:08:42
SolutionsolutionCharlie2017-11-27 13:06:02
SolutionAnswerchun2017-11-27 08:55:24
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