36=2^2 * 3^2
so 36^2=2^4 * 3^4
number of factors = (4+1)*(4+1)=25
option D
factors
This topic has expert replies
Source: Beat The GMAT — Problem Solving |
-
gmatmachoman
- Legendary Member
- Posts: 2326
- Joined: Mon Jul 28, 2008 3:54 am
- Thanked: 173 times
- Followed by:2 members
- GMAT Score:710
36 * 96 = 6 * 6 * 6 * 16dkumar.83 wrote:Thanks for the prompt reply. Just to add, incase the question asks the number of factors of 36*96, then what will be the answer?
= 2 * 3 * 2 * 3 * 2*3 * 2^4
= 2^7 *3 ^3
=
No of factors : (7+1) * (3+1)
8 * 4
= 32
Hope this helps!!
-
liferocks
- Legendary Member
- Posts: 576
- Joined: Sat Mar 13, 2010 8:31 pm
- Thanked: 97 times
- Followed by:1 members
just to generalizegmatmachoman wrote:36 * 96 = 6 * 6 * 6 * 16dkumar.83 wrote:Thanks for the prompt reply. Just to add, incase the question asks the number of factors of 36*96, then what will be the answer?
= 2 * 3 * 2 * 3 * 2*3 * 2^4
= 2^7 *3 ^3
=
No of factors : (7+1) * (3+1)
8 * 4
= 32
Hope this helps!!
for any number n=a^p *b^q..so on where a,b ..etc are prime number of factors is
(p+1)(q+1)...
"If you don't know where you are going, any road will get you there."
Lewis Carroll
Lewis Carroll
-
The Jock
- Master | Next Rank: 500 Posts
- Posts: 207
- Joined: Mon Oct 06, 2008 12:22 am
- Location: India
- Thanked: 5 times
- Followed by:3 members
Hey dkumar.83,
I have given a full explanation on this topic in one of my post in my blog. I am sure that you would like to have a look at it.
Finding the number of factors(or divisors) of a given number(composite number):
https://mbayogi.wordpress.com/2010/04/28 ... tics-gyan/
I have given a full explanation on this topic in one of my post in my blog. I am sure that you would like to have a look at it.
Finding the number of factors(or divisors) of a given number(composite number):
https://mbayogi.wordpress.com/2010/04/28 ... tics-gyan/
-
liferocks
- Legendary Member
- Posts: 576
- Joined: Sat Mar 13, 2010 8:31 pm
- Thanked: 97 times
- Followed by:1 members
yes.Thouraya wrote:Hey,
Is it a rule that to know the number of factors we take the exponent and add 1 to it?
Thank you!
for any number n=a^p *b^q..so on where a,b ..etc are prime number of factors is
(p+1)(q+1)...
"If you don't know where you are going, any road will get you there."
Lewis Carroll
Lewis Carroll
-
hardik.jadeja
- Legendary Member
- Posts: 535
- Joined: Fri Jun 08, 2007 2:12 am
- Thanked: 87 times
- Followed by:5 members
- GMAT Score:730
Guys,
there is a simple rule that a perfect square will always have odd number of factors.
Only option D is odd. Rest all are even. Absolutely no calculations required.
Hope that helps.
there is a simple rule that a perfect square will always have odd number of factors.
Only option D is odd. Rest all are even. Absolutely no calculations required.
Hope that helps.
