VJesus12 wrote:How many factors does 36^2 have?
A. 2
B. 8
C. 24
D. 25
E. 26
The OA is the option D.
How can I solve this question is a fast way? Can anyone give me a good explanation? Thanks.
-------ASIDE-------------------
If the
prime factorization of N = (p^
a)(q^
b)(r^
c) . . . (where p, q, r, etc are different prime numbers), then N has a total of (
a+1)(
b+1)(
c+1)(etc) positive divisors.
Example: 14000 = (2^
4)(5^
3)(7^
1)
So, the number of positive divisors of 14000 = (
4+1)(
3+1)(
1+1) =(5)(4)(2) = 40
---NOW ONTO THE QUESTION-----------------
36 = (2)(2)(3)(3)
So, 36² = (36)(36)
= (2)(2)(3)(3)(2)(2)(3)(3)
= (2^
4)(3^
4)
So, the number of positive divisors of 36² = (
4+1)(
4+1)
= (5)(5)
= 25
Answer:
D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
