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Which of the following could be the units digit 98^x

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Which of the following could be the units digit 98^x [#permalink] New post 30 Jul 2017, 08:50
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Question Stats:

50% (00:51) correct 50% (00:39) wrong based on 16 sessions


Which of the following could be the units digit \(98^x\), where x is an integer greater than 1?

Indicate all such digits:

❑ zero

❑ 1

❑ 2

❑ 3

❑ 4

❑ 5

❑ 6

❑ 7

❑ 8

❑ 9

[Reveal] Spoiler:
C,E,G,I
[Reveal] Spoiler: OA

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Re: Which of the following could be the units digit 98^x [#permalink] New post 03 Aug 2017, 15:43
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Expert's post
Carcass wrote:
Which of the following could be the units digit \(98^x\), where x is an integer greater than 1?

Indicate all such digits:

❑ zero

❑ 1

❑ 2

❑ 3

❑ 4

❑ 5

❑ 6

❑ 7

❑ 8

❑ 9

[Reveal] Spoiler:
C,E,G,I


98^1 = 98
98^2 = (98)(98) = ---4 [note: we need only recognize that the units digit of 98^2 will be equal to the units digit of (8)(8), which is 4]
98^3 = (98)(98)(98) = (---4)(98) = ----2 [note: we need only recognize that the units digit of (---4)(98) will be equal to the units digit of (4)(8), which is 2]
98^4 = (98)(98)(98)(98) = (----2)(98) = ----6
98^5 = (98)(98)(98)(98)(98) = (----6)(98) = ----8

At this point, we are repeating the pattern. So, there's no need to continue.
The pattern of units digits will be 8, 4, 2, 6, 8, 4, 2, 6, 8, etc

Answer: 2, 4, 6, 8 (C, E, G, I)

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com
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Re: Which of the following could be the units digit 98^x [#permalink] New post 04 Aug 2017, 06:41
Expert's post
Honestly,

I do not think such question adhere to the standards..........
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Re: Which of the following could be the units digit 98^x   [#permalink] 04 Aug 2017, 06:41
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Which of the following could be the units digit 98^x

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