What is the units digit of 7 raised to the power 2026?
Answer and explanation
Correct answer: C. 9, because the units digits cycle 7, 9, 3, 1 and 2026 leaves remainder 2
- Step 1: The units digits of 7, 49, 343, 2401 are 7, 9, 3, 1 and then repeat with period 4.
- Step 2: 2026 = 4 x 506 + 2, so the units digit is the second in the cycle: 9.
Answer
9.
Why not the others: 7 is the first in the cycle, 3 the third and 1 the fourth; the exponent mod 4 is 2.
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