K=1! +2! +3! …+25!. What would be the last digit of K?

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K=1! +2! +3! …….+25!

What would be the last digit of K?

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    Answer – 3


    Explanation-

    K = 1! + 2! + 3! …….. + 25!
    Last digit of K = Last digit (1!) + Last digit (2!) + Last digit (3!) …….. + Last digit (25!)
    Last digit (1!) = 1
    Last digit (2!) = 2
    Last digit (3!) = 6
    Last digit (4!) = 4
    Last digit (5!) = 0
    Last digit (6!) = 0
    .
    .
    .
    Last digit (25!) = 0

    Please note that Last digit (n!) such that n > 4 will be 0

    Last digit of K = 1 + 2 + 6 + 4 + 0 + 0 + 0 … 0 = 3

    MrPuzzleFry Genius Answered on 11th September 2015.
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