GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 14 Oct 2019, 03:43

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Number of factors

Author Message
TAGS:

### Hide Tags

Intern
Joined: 04 Oct 2015
Posts: 12

### Show Tags

14 Oct 2015, 06:29
1
Number of factors of A = 2^3 * 5^7 * 7^2

Math Expert
Joined: 02 Sep 2009
Posts: 58313

### Show Tags

14 Oct 2015, 11:19
Sujan Sareen wrote:
Number of factors of A = 2^3 * 5^7 * 7^2

Finding the Number of Factors of an Integer:

First make prime factorization of an integer $$n=a^p*b^q*c^r$$, where $$a$$, $$b$$, and $$c$$ are prime factors of $$n$$ and $$p$$, $$q$$, and $$r$$ are their powers.

The number of factors of $$n$$ will be expressed by the formula $$(p+1)(q+1)(r+1)$$. NOTE: this will include 1 and n itself.

Example: Finding the number of all factors of 450: $$450=2^1*3^2*5^2$$

Total number of factors of 450 including 1 and 450 itself is $$(1+1)*(2+1)*(2+1)=2*3*3=18$$ factors.

Check for more here: math-number-theory-88376.html

So, the number of factors of $$2^3 * 5^7 * 7^2$$ is $$(3 + 1)(7 + 1)(2 + 1) = 96$$.
_________________
CEO
Joined: 12 Sep 2015
Posts: 3990

### Show Tags

23 Oct 2015, 13:04
1
We have a free video that explains the rule that Bunuel used - http://www.gmatprepnow.com/module/gmat- ... /video/828

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
Manhattan Prep Instructor
Joined: 22 Mar 2011
Posts: 1564

### Show Tags

29 Oct 2015, 17:52
I'm curious why you say that 192 is the real answer. Do you have a copy of the full question? (If that's all there is, then it's simply an error. Bunuel, of course, is correct.)
_________________

Dmitry Farber | Manhattan Prep GMAT Instructor | San Diego

Manhattan GMAT Discount | Manhattan GMAT Course Reviews | View Instructor Profile |
Manhattan GMAT Reviews
Non-Human User
Joined: 09 Sep 2013
Posts: 13088

### Show Tags

29 Jan 2018, 00:51
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Number of factors   [#permalink] 29 Jan 2018, 00:51
Display posts from previous: Sort by