If n is an integer greater than 5.3, then n! must be divisible by which of the following numbers?

This topic has expert replies
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 am
Location: Grand Central / New York
Thanked: 470 times
Followed by:34 members
BTGmoderatorDC wrote:
Tue May 26, 2020 7:14 pm
If n is an integer greater than 5.3, then n! must be divisible by which of the following numbers?

A. 7
B. 11
C. 12
D. 13
E. 14

OA C

Source: Princeton Review
Since this is a must be true question, we must take the minimum value of n, i.e., n = 6.

So, we have to choose an option that must divide 6! = 1.2.3.4.5.6. Let's take all options, one by one.

A. 7

Since 7 is a prime number and 6! does not have a 7, it's incorrect.

B. 11

Similarly, since 11 is a prime number and 6! does not have an 11, it's incorrect.

C. 12

Correct. 12 can be factored as 2*2*3. We see that in 6! = 1.2.3.4.5.6, there are ample no. of 2s and 3s. So, 12 must divide 6!.

D. 13

Similarly, since 13 is a prime number and 6! does not have a 13, it's incorrect.

E. 14

14 can be factored as 2*7, and since 7 is a prime number and 6! does not have a 7, it's incorrect.

The correct answer: C

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: Manhattan Review Warangal | Hyderabad | GRE Prep Mumbai | Visakhapatnam GRE Coaching | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.