Which of the following is not a perfect square?
1. 100856
2. 325137
3. 945729
4. All of these
5. None of these
OA=D
Could someone give me the best approach to solve this PS question? Please.
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Which of the following is not a perfect square?
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Gmat_mission
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Which of the following is not a perfect square?
Sun Jun 24, 2018 11:45 pm
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Jeff@TargetTestPrep
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Tue Jun 26, 2018 5:21 pm
Gmat_mission wrote:
We know that a perfect square must end with 0, 1, 4, 5, 6, or 9, so we can see choice 2 is not a perfect square.
Which of the following is not a perfect square?
1. 100856
2. 325137
3. 945729
4. All of these
5. None of these
1. 100856
2. 325137
3. 945729
4. All of these
5. None of these
Now let’s check choice 1. Since 310^2 = 96,100 and 320^2 = 102,400, then, if 100,856 is a perfect square, it must be the square of either 314 or 316 since either one of these integers will produce a units digit of 6 when squared. However, since 314^2 = 98,596 and 316^2 = 99,856, we see that choice 1 is a not a perfect square, either.
Since both choices 1 and 2 are not perfect squares, we will conclude that the correct answer must be choice 4 (even though we have not verified that choice 3 is not a perfect square).
Answer: 4
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