Which of the following is a perfect square?

Question

A. 55,225
B. 55,235
C. 55,245
D. 55,255
E. 55,295

kumarparitosh123 · Answer

The initial two digits are same for all. The last three are different. So 225 is a perfect square.
Hence A.

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pushpitkc · Answer

5  is a prime number which will divide the answer option
A perfect square will have to be have a power of 2 for every prime factor, 
so  5^2(25)  divides this number.

Of the options available, Only  Option A(55225)  is a number which 25 divides!

sashiim20 · Answer

Last digit of options are ending in  5 . Hence all numbers are divisible by  5

Square of  5  ends in  25

Only option is  55,225

Answer (A)...

19W · Answer

A. 55,225  as only 225 is perfect square among the last three digits of the options.

stne · Answer

Just for learning sake . Can anybody, please provide me the prime factorization of option A. Thank you.

soapbolt · Answer

stne FYI Prime Factorization of 55225 =( 5^2 ) * (47^2) Hope it helps

aa008 · Answer

5^2 * 47^2

stne · Answer

Thank you , but how did you calculate that? Without the OA , how would you know that 47^2 will yield 2209?

soapbolt · Answer

Hi stne
As you know--> First of all we start with smallest prime no. and start factorizing . Here in our case its 5

After doing so we come up with the number 2209
Now to know which prime number could be the factor(s) of 2209 we have to check all the prime numbers which are less than \(\sqrt{2209}\)

i.e. approx prime no < 50 ( since \(50^2 = 2500\))

Also Unit digit of 2209 is 9 hence Prime number should have either 7 or 3 as its unit digit.

On quickly checking, 2209 is not divisible by 3 , 7 , 13 , 17
So i move to back of our list i.e. Prime number <50

I picked Number 47 and hence on checking i got my solution

Hope it helps

Dipu10 · Answer

Does the same technique work for below question as well ? Option C is the correct answer here but 856 is not a perfect square. Any idea why the same approach is not working here?

What is the largest five-digit which is a perfect square ?

(A) 97344
(B) 98596
(C) 99856
(D) 99956
(E) 99996

CrackverbalGMAT · Answer

Which of the following is a perfect square?

A. 55,225
B. 55,235
C. 55,245
D. 55,255
E. 55,295

Since all the answer options i.e square of a number are ending with '5' ,we can conclude that the number should also ends with '5'.

Square of any number ending with '5' always ends with '25'.

Only Option A will satisfy the condition. So Option B,C,D,E will not be a perfect square. Hence eliminated.

Option A is the answer.

Thanks,
Clifin J Francis.

Malar95 · Answer

Given the range. (A) felt like the most apt guess. A risky thing to do in the real exam or possibly a time saving thing.

Which of the following is a perfect square?

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Which of the following is a perfect square?

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