What is the greatest value of x such that 5^x is a factor of 25! ?
A. 2
B. 3
C. 4
D. 5
E. 6
The OA is E.
I don't understand this PS question. Please, can any expert assist me with it? Thanks.
What is the greatest value of x such that 5^x is a factor...
This topic has expert replies
- DavidG@VeritasPrep
- Legendary Member
- Posts: 2663
- Joined: Wed Jan 14, 2015 8:25 am
- Location: Boston, MA
- Thanked: 1153 times
- Followed by:128 members
- GMAT Score:770
Effectively, we want the number of 5's in the prime factorization of 25!. So, let's examine all the multiples of 5 in 25!swerve wrote:What is the greatest value of x such that 5^x is a factor of 25! ?
A. 2
B. 3
C. 4
D. 5
E. 6
The OA is E.
I don't understand this PS question. Please, can any expert assist me with it? Thanks.
5 ---> one 5
10 --> one 5
15---> one 5
20 ---> one 5
25 = 5^2 ---> two 5's
Add 'em up: and we've got 6 total. The answer is E
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7223
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
Prime factorizing all the multiples of 5 up to 25, we have:swerve wrote:What is the greatest value of x such that 5^x is a factor of 25! ?
A. 2
B. 3
C. 4
D. 5
E. 6
The OA is E.
I don't understand this PS question. Please, can any expert assist me with it? Thanks.
25 = 5^2
20 = 5^1 x 2^2
15 = 5^1 x 3
10 = 5^1 x 2
5 = 5^1
Thus, we see that there are 6 factors of 5 in 25! and thus the maximum value of x is 6.
Answer: E
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews