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# If x is a positive integer, what is the units digit of

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Founder
Joined: 18 Apr 2015
Posts: 6200
Followers: 99

Kudos [?]: 1199 [0], given: 5709

If x is a positive integer, what is the units digit of [#permalink]  26 Aug 2017, 02:05
Expert's post
00:00

Question Stats:

50% (01:11) correct 50% (00:00) wrong based on 10 sessions

If x is a positive integer, what is the units digit of $$(24)^{5+2x}$$ + $$(36)^6$$ + $$(17)^3$$

(A) 2
(B) 3
(C) 4
(D) 6
(E) 8
[Reveal] Spoiler: OA

_________________
Director
Joined: 03 Sep 2017
Posts: 521
Followers: 1

Kudos [?]: 355 [0], given: 66

Re: If x is a positive integer, what is the units digit of [#permalink]  18 Sep 2017, 02:20
Carcass wrote:
If x is a positive integer, what is the units digit of $$(24)^{5+2x}$$ + $$(36)^6$$ + $$(17)^3$$

(A) 2
(B) 3
(C) 4
(D) 6
(E) 8
a n

Any hint for this one? I computed 36^6 which terminates with a 6, 17^3 terminates with a 3 and 24^(5+2x) can be rewritten as 24^5*24^2x where 24^5 terminates with a 4 and 24^2x terminates with a 6 for whatever value of x. Thus, the 24 term terminates with a 4. Summing three numbers terminating with 6, 3 and 4, it results a number terminating with 3, thus answer B seems right to me. However, the answer seems to be A. why?
Founder
Joined: 18 Apr 2015
Posts: 6200
Followers: 99

Kudos [?]: 1199 [0], given: 5709

Re: If x is a positive integer, what is the units digit of [#permalink]  18 Sep 2017, 05:58
Expert's post
You are right Sir.

Maybe a typo or a wrong answer. Anyhow, I have fixed. Thank to pointed out Sir.

Regards
_________________
Re: If x is a positive integer, what is the units digit of   [#permalink] 18 Sep 2017, 05:58
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