What is the unit digit of \(3^{65} \times 7^{42}\)?
A. 3
B. 7
C. 1
D. 9
1 answer
Best answer
Answer: B. 7
Answer: (B) 7
Unit digits of powers of 3 cycle 3, 9, 7, 1; \(65 = 4 \times 16 + 1\), so \(3^{65}\) ends in 3. Powers of 7 cycle 7, 9, 3, 1; \(42 = 4 \times 10 + 2\), so \(7^{42}\) ends in 9. \(3 \times 9 = 27\): unit digit 7.
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· 27 Oct 2026
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