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If k is a positive integer, and if the units’ digit
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02 Aug 2021, 14:07
02 Aug 2021, 14:07
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Question Stats:
89% (00:58) correct
10% (03:09) wrong based on 28 sessions
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If \(k\) is a positive integer, and if the units’ digit of \(k^2\) is 1 and the units' digit of \((k+1)^2\) is 0, what is the units' digit of \((k+2)^2\)?
(A) 1
(B) 3
(C) 5
(D) 7
(E) 9
(A) 1
(B) 3
(C) 5
(D) 7
(E) 9
Retired Moderator
Joined: 19 Nov 2020
Posts: 326
Given Kudos: 64
GRE 1: Q160 V152
If k is a positive integer, and if the units’ digit
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02 Aug 2021, 16:06
02 Aug 2021, 16:06
2
Of all integers only those ending with 1 and 9 result in squred integer's unit=1.
Given 1 and 9 or N1 and N9 are added by 1, the squared digits will ending in 0 for 9 or N9.
When added by 2, the unit's digit of N9 will be 1 for the squared integer results in unit's digit of 1 too. Answer is A
Given 1 and 9 or N1 and N9 are added by 1, the squared digits will ending in 0 for 9 or N9.
When added by 2, the unit's digit of N9 will be 1 for the squared integer results in unit's digit of 1 too. Answer is A
Carcass wrote:
If \(k\) is a positive integer, and if the units’ digit of \(k^2\) is 1 and the units' digit of \((k+1)^2\) is 0, what is the units' digit of \((k+2)^2\)?
(A) 1
(B) 3
(C) 5
(D) 7
(E) 9
(A) 1
(B) 3
(C) 5
(D) 7
(E) 9
gmatclubot
If k is a positive integer, and if the units’ digit [#permalink]
02 Aug 2021, 16:06
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