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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