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What is the units digit of (3^11)(4^13)?

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What is the units digit of (3^11)(4^13)?

by Max@Math Revolution » Sat Jan 23, 2016 10:31 pm
What is the units digit of (3^11)(4^13)?


A. 2
B. 4
C. 6
D. 7
E. 8


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by Max@Math Revolution » Wed Jan 27, 2016 5:28 pm
What is the units digit of (3^11)(4^13)?


A. 2 B. 4 C. 6 D. 7 E. 8


-> The ones place of (~3)^n repeats after 4 times like 39713. The ones place of (~4)^n repeats after 2 times like 464. Then, 3^11=3^4*2+33^3., which is (3^11)(4^13) (3^3)(~4)=(~7)(~4)=~8. Therefore, the answer is E.
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