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How many whole numbers

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How many whole numbers [#permalink] New post 29 Dec 2016, 09:22
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Question Stats:

50% (01:13) correct 50% (01:19) wrong based on 8 sessions
How many whole numbers less than 81 are NOT equal to squares of whole numbers ?

(A) 9
(B) 70
(C) 71
(D) 72
(E) 73
[Reveal] Spoiler: OA

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Re: How many whole numbers [#permalink] New post 29 Sep 2017, 07:16
The perfect squares less than 81 are 0, 1, 4, 9, 16, 25, 36, 49, 64.

Now, the question asks for numbers less than 81, thus I would not include 81 in my count. Thus, we have 80 numbers minus 9 perfect squares that are 71 numbers. However, the answer is 72.

Now, is GRE considering 0 a perfect square? Because it is a discussed issue among mathematicians and if we do not take it into consideration, we would obtain 72.
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Re: How many whole numbers [#permalink] New post 05 Oct 2017, 11:01
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Carcass wrote:
How many whole numbers less than 81 are NOT equal to squares of whole numbers ?

(A) 9
(B) 70
(C) 71
(D) 72
(E) 73


Whole numbers: 0, 1, 2, 3, 4,.....

There's a TOTAL of 81 whole numbers that are LESS THAN 81: 0, 1, 2, 3, 4, . . . 80

The squares of whole numbers are: 0, 1, 4, 9, 16, 25, 36, 49, 64 (9 altogether)

So, the number of whole numbers less than 81 are NOT equal to squares of whole numbers = 81 - 9 = 72

Answer:
[Reveal] Spoiler:
D


Cheers,
Brent
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Re: How many whole numbers   [#permalink] 05 Oct 2017, 11:01
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