What is the unit digit in the expansion of 67^{32}?

  1. A. 1
  2. B. 3
  3. C. 7
  4. D. 9

Correct Answer: A. 1

Explanation

The unit digit depends on 7^{32}. The cyclicity of the unit digit of powers of 7 is 4 (7, 9, 3, 1). Since 32 is a perfect multiple of 4, the unit digit is 1.

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