Question 44
EasyOriginal questionWhat is the unit digit of ?
Show the answer and explanation
CorrectNot quiteAnswer A
Correct answer: A
Explanation
Powers of 9 end in 9, 1, 9, 1, … — odd powers end in 9, even powers in 1.
42 is even, so the unit digit is 1.
Worth noting
9 has a cycle of just 2, so only the parity of the power matters.
- Concept
- Cyclicity of unit digits of powers of 9
- Typical timeTypical
- 35 s
- Your timeYours
- —
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