+0  
 
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135
3
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What is the units digit of 1! + 2! + 3! + 4! + ... + 50!

 Jul 6, 2018
 #1
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+2

Just add the first 4 or 5 numbers, because after that they all end in zeros:

1! + 2! + 3! + 4! + 5! =

1  +  2 +  6  + 24 + 120 =153 - so, units digit is 3.

 Jul 6, 2018

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