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# Perfect square

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Intern
Joined: 17 Oct 2014
Posts: 18
Location: India
Concentration: Healthcare, Nonprofit
GMAT 1: 700 Q49 V37
GPA: 3.7
WE: Research (Pharmaceuticals and Biotech)

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03 Dec 2014, 00:30
The number theory states that :
A perfect square ALWAYS has an ODD number of Odd-factors, and EVEN number of Even-factors.
Could you please explain what this means
If i have a number say: 4624.that will be 17*17*2*2*2*2
which is 2 factors of the odd number 17
Intern
Joined: 17 Oct 2014
Posts: 29

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03 Dec 2014, 06:56
Motivatedtowin wrote:
The number theory states that :
A perfect square ALWAYS has an ODD number of Odd-factors, and EVEN number of Even-factors.
Could you please explain what this means
If i have a number say: 4624.that will be 17*17*2*2*2*2
which is 2 factors of the odd number 17

Hi Motivated,

Interesting trivia! As a mathematician, I'm always interested to learn facts like that--but as a GMAT instructor, I always caution students about focusing too much on details like this that are extremely unlikely to appear on your exam!

As for your specific question, you are getting factors confused with prime factors. The rule you mentioned applies to the total list of factors of 4624, i.e. 1 * 4624, 2 * 2312, 4 * 1156...

Hope this helps!
Intern
Joined: 17 Oct 2014
Posts: 18
Location: India
Concentration: Healthcare, Nonprofit
GMAT 1: 700 Q49 V37
GPA: 3.7
WE: Research (Pharmaceuticals and Biotech)

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03 Dec 2014, 08:35
EliLTG wrote:
Motivatedtowin wrote:
The number theory states that :
A perfect square ALWAYS has an ODD number of Odd-factors, and EVEN number of Even-factors.
Could you please explain what this means
If i have a number say: 4624.that will be 17*17*2*2*2*2
which is 2 factors of the odd number 17

Hi Motivated,

Interesting trivia! As a mathematician, I'm always interested to learn facts like that--but as a GMAT instructor, I always caution students about focusing too much on details like this that are extremely unlikely to appear on your exam!

As for your specific question, you are getting factors confused with prime factors. The rule you mentioned applies to the total list of factors of 4624, i.e. 1 * 4624, 2 * 2312, 4 * 1156...

Hope this helps!

Thank you so much ...The exam already has too much to study and work in itself But i just came across this and could not understand..So basically..say for a smaller number like 36:1*2*2*3*3, number of odd factors=3(ODD) and number of even factors equals 2(EVEN)
Intern
Joined: 17 Oct 2014
Posts: 29

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03 Dec 2014, 10:12
Not quite!
The factors of 36 are:

1, 36
2, 18
3, 12
4, 9
6, 6

So, the odd factors are: 1, 3, and 9;
The even factors are 2, 4, 6, 12, 18, 36.
Does this help?
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8787
Location: Pune, India

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03 Dec 2014, 18:50
1
Motivatedtowin wrote:
The number theory states that :
A perfect square ALWAYS has an ODD number of Odd-factors, and EVEN number of Even-factors.
Could you please explain what this means
If i have a number say: 4624.that will be 17*17*2*2*2*2
which is 2 factors of the odd number 17

Here are a few interesting things about factors of perfect squares:

ONLY perfect squares will have odd number of total factors and ALL perfect squares will have an odd number of total factors.

A perfect square always has odd number of odd factors.

A perfect square always has even number of even factors.

The sum of all factors of a perfect square is always odd but if the sum of all factors of a number is odd, we cannot say that it must be a perfect square.

I have explained the why and how of each one of these statements in this post: http://www.veritasprep.com/blog/2010/12 ... t-squares/
You wouldn't need to "learn" anything once you go through it.
_________________

Karishma
Veritas Prep GMAT Instructor

Intern
Joined: 17 Oct 2014
Posts: 18
Location: India
Concentration: Healthcare, Nonprofit
GMAT 1: 700 Q49 V37
GPA: 3.7
WE: Research (Pharmaceuticals and Biotech)

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04 Dec 2014, 04:33
Thanks so much for the replies...Finally clarity
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Joined: 09 Sep 2013
Posts: 9423

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16 May 2017, 05:17
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Re: Perfect square &nbs [#permalink] 16 May 2017, 05:17
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