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# 17^27 has a units digit of: 1 2 3 7 9

Author Message
Manager
Joined: 21 Jun 2006
Posts: 232
17^27 has a units digit of: 1 2 3 7 9  [#permalink]

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26 Jun 2007, 21:43
2
00:00

Difficulty:

(N/A)

Question Stats:

100% (00:16) correct 0% (00:00) wrong based on 76 sessions

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17^27 has a units digit of:
1
2
3
7
9

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Senior Manager
Joined: 12 Jun 2006
Posts: 428

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26 Jun 2007, 21:57
1
units digit cycle is 7,9,3,1,7,9,3,1,7 etc. the 27th iteration is 9.
Senior Manager
Joined: 04 Jun 2007
Posts: 272

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26 Jun 2007, 22:36
1
Himalayan wrote:
ArvGMAT wrote:
17^27 has a units digit of:
1
2
3
7
9

3.

Agree with 3. It will be the third (remainder in 27/4) term.
Director
Joined: 14 Jan 2007
Posts: 600

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27 Jun 2007, 02:38
(17^4)^6 *17^3
Units digits = 1 * 3 = 3
Director
Joined: 06 Sep 2006
Posts: 503

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27 Jun 2007, 09:41
Capturing only unit digits
7^1 = 7
7*7 = 9 (only unit digit)
9*7 = 3
3*7 = 1
1*7 = 7

So pattern repeat itself after 4 iteration.

7 9 3 1 7 9 3 1...

3. I think it is C.
Non-Human User
Joined: 09 Sep 2013
Posts: 13257
Re: 17^27 has a units digit of: 1 2 3 7 9  [#permalink]

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13 Apr 2019, 04:36
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Re: 17^27 has a units digit of: 1 2 3 7 9   [#permalink] 13 Apr 2019, 04:36
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