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unit digit

by mehrasa » Sun Sep 11, 2011 12:30 pm
what is the last digit of 3^(3^3)?
1
3
6
7
9


to me the answer is D
3^(3^3)= 3^(27) since the last digit in power 3 will be 3,9,7,1 and this cycle repeat every 4 and power of the Q is 27, then the 27th power will be 7
what is ur ideas?
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by pemdas » Sun Sep 11, 2011 1:44 pm
the question is 3^27?
cycles of 3 => (1) 3, (2) 9, (3) 7, (4) 1 ... the power of 27 will return the unit's digit 7;
27:4=6 and 3 places to the right i.e. the power of 3

d
mehrasa wrote:what is the last digit of 3^(3^3)?
1
3
6
7
9


to me the answer is D
3^(3^3)= 3^(27) since the last digit in power 3 will be 3,9,7,1 and this cycle repeat every 4 and power of the Q is 27, then the 27th power will be 7
what is ur ideas?
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