Last visit was: 21 Apr 2026, 13:27 It is currently 21 Apr 2026, 13:27
Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
guerrero25
Joined: 10 Apr 2012
Last visit: 13 Nov 2019
Posts: 244
Own Kudos:
5,199
 [6]
Given Kudos: 325
Location: United States
Concentration: Technology, Other
GPA: 2.44
WE:Project Management (Telecommunications)
Posts: 244
Kudos: 5,199
 [6]
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 21 Apr 2026
Posts: 109,729
Own Kudos:
810,458
 [5]
Given Kudos: 105,798
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,729
Kudos: 810,458
 [5]
3
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
General Discussion
User avatar
justdoitxxxxx
Joined: 16 May 2015
Last visit: 26 Oct 2015
Posts: 18
Own Kudos:
Given Kudos: 11
Posts: 18
Kudos: 32
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 18 Apr 2026
Posts: 11,230
Own Kudos:
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,230
Kudos: 44,982
Kudos
Add Kudos
Bookmarks
Bookmark this Post
katzzzz
Just want to clear a concept that the formula to compute the no of factors of a number includes identical factors?

2^ 1 ∗3^ 2 ∗5^ 1 =90

therefore, for perfect square, we need to eliminate the identical factors?

Thanks in advance.

The number of factors that you get is only the distinct factors and does not count the identical factors in case of perfect square twice..
eg 36=2^2*3^2..
no of factors= 3*3=9..
they are 1,2,3,4,6,9,12,18,36..
hope it clears the doubt
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 21 Apr 2026
Posts: 6,976
Own Kudos:
16,891
 [2]
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
Expert
Expert reply
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 6,976
Kudos: 16,891
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
katzzzz
Just want to clear a concept that the formula to compute the no of factors of a number includes identical factors?

2^ 1 ∗3^ 2 ∗5^ 1 =90

therefore, for perfect square, we need to eliminate the identical factors?

Thanks in advance.

Please refer two distinct concepts to calculate factors of any Number

1) By writing the Number as product of two Integers

2) By prime factorization and multiplying the powers of Distinct prime after adding one in each power of Primes
Attachments

File comment: www.GMATinsight.com
Factors.jpg
Factors.jpg [ 112.78 KiB | Viewed 18947 times ]

User avatar
Sujithz001
Joined: 09 Jun 2024
Last visit: 06 Feb 2026
Posts: 101
Own Kudos:
Given Kudos: 75
Posts: 101
Kudos: 46
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel Just to confirm - If we're asked to include negative factors as well, then it's 2 x 18 = 36 right?
Bunuel
How many positive integers are factors of 90?

A. 6
B. 8
C. 9
D. 10
E. 12


Determining the Number of Positive Factors of a Positive Integer \(n\):

First, perform the prime factorization of an integer \(n\). Let \(n = p^a * q^b * r^c\), where \(p\), \(q\), and \(r\) are the prime factors of \(n\), and \(a\), \(b\), and \(c\) are their respective powers.

The number of positive factors of \(n\) can be determined by the formula \((a+1)(b+1)(c+1)\). NOTE: This includes 1 and \(n\) itself.

For example, to find the number of positive factors of 450, we first perform its prime factorization: \(450 = 2^1 * 3^2 * 5^2\). The total number of positive factors of 450, including 1 and 450, is \((1+1)(2+1)(2+1) = 18\) positive factors.

According to the above, 90, which is equal to \(2*3^2*5\), has \((1+1)(2+1)(1+1) = 12\) positive factors, namely 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, and 90.


Answer: E
Similar questions to practice:
https://gmatclub.com/forum/how-many-odd ... 06082.html
https://gmatclub.com/forum/how-many-fac ... 26422.html
https://gmatclub.com/forum/how-many-dif ... 30628.html
https://gmatclub.com/forum/how-many-dis ... 44326.html

Hope it helps.
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 21 Apr 2026
Posts: 109,729
Own Kudos:
Given Kudos: 105,798
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,729
Kudos: 810,458
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Sujithz001
Bunuel Just to confirm - If we're asked to include negative factors as well, then it's 2 x 18 = 36 right?
Bunuel
How many positive integers are factors of 90?

A. 6
B. 8
C. 9
D. 10
E. 12


Determining the Number of Positive Factors of a Positive Integer \(n\):

First, perform the prime factorization of an integer \(n\). Let \(n = p^a * q^b * r^c\), where \(p\), \(q\), and \(r\) are the prime factors of \(n\), and \(a\), \(b\), and \(c\) are their respective powers.

The number of positive factors of \(n\) can be determined by the formula \((a+1)(b+1)(c+1)\). NOTE: This includes 1 and \(n\) itself.

For example, to find the number of positive factors of 450, we first perform its prime factorization: \(450 = 2^1 * 3^2 * 5^2\). The total number of positive factors of 450, including 1 and 450, is \((1+1)(2+1)(2+1) = 18\) positive factors.

According to the above, 90, which is equal to \(2*3^2*5\), has \((1+1)(2+1)(1+1) = 12\) positive factors, namely 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, and 90.


Answer: E
Similar questions to practice:
https://gmatclub.com/forum/how-many-odd ... 06082.html
https://gmatclub.com/forum/how-many-fac ... 26422.html
https://gmatclub.com/forum/how-many-dif ... 30628.html
https://gmatclub.com/forum/how-many-dis ... 44326.html

Hope it helps.
________________
Right.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,954
Own Kudos:
Posts: 38,954
Kudos: 1,117
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Math Expert
109729 posts
Tuck School Moderator
853 posts