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The digit in the unit's place of the number (67)25 - 1 must be -
Answer & Solution
Correct Answer:
Option
B
Unit digit of (67)25 = Unit digit of 725
Unit digit of 74 is 1 and so the unit digit of (74)6 is 1
∴ Unit digit of 725 = (1 × 7) = 7
Hence, the unit digit of (725 - 1) is (7 - 1) = 6
Unit digit of 74 is 1 and so the unit digit of (74)6 is 1
∴ Unit digit of 725 = (1 × 7) = 7
Hence, the unit digit of (725 - 1) is (7 - 1) = 6
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