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| Question 487120:  which of the following could be the units digit of 57^n where n is a positive integer?  Indicate all such digits:
 A.) 0
 B.) 1
 C.) 2
 D.) 3
 E.) 4
 F.) 5
 G.) 6
 H.) 7
 I.) 8
 J.) 9
 
 Answer by richard1234(7193)
      (Show Source): 
You can put this solution on YOUR website! Same units digits as 7^n. 7^1 ≡ 7 (mod 10), 7^2 ≡ 9, 7^3 ≡ 3, 7^4 ≡ 1, 7^5 ≡ 7, and the pattern repeats. The only possible digits are 1,3,7,9.
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