What is the unit digit of 7^25?
A1
B3
C7
D9
Answer & Solution
Correct answer: C. 7
Unit digits of 7^n cycle: 7, 9, 3, 1, 7, 9, 3, 1... (period 4). 25 mod 4 = 1, so unit digit matches 7^1 = 7.
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