Factorial Problem

Number Theory Level 1

Find the last digit of 2016 ! 2016! .


The answer is 0.

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Nathan Laurence by Nathan Laurence , 19, Indonesia

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2 solutions

Nathan Laurence
Nov 23, 2016

Since 2016 ! 2016! is equal to 2016 ∗ 2015 ∗ . . . ∗ 2000 ∗ . . . ∗ 1 2016 * 2015 * ... * 2000 * ... * 1 , the last digit is 0

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Actually, last digit of n! is 0 for n>=5 :)

C B - 4 years, 6 months ago

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Yes that's true, thx for 5 ! = 120 5! = 120 with 0 0 on the last digit :)

Jason Chrysoprase - 4 years, 6 months ago

2016! = 1x2x3x4x5x6......x2016, ends with a zero because 2x5=10

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