Is the integer p divisible by 4?

This topic has expert replies
Legendary Member
Posts: 2898
Joined: Thu Sep 07, 2017 2:49 pm
Thanked: 6 times
Followed by:5 members

Is the integer p divisible by 4?

by Vincen » Wed Oct 11, 2017 6:43 pm
Is the integer p divisible by 4?

(1) p < 123
(2) p is the product of 5 consecutive positive integers.

The OA is B.

Clearly statement (1) is not sufficient. But, how can I ensure the statement (2) is sufficient?

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

by Jay@ManhattanReview » Wed Oct 11, 2017 11:05 pm
Vincen wrote:Is the integer p divisible by 4?

(1) p < 123
(2) p is the product of 5 consecutive positive integers.

The OA is B.

Clearly statement (1) is not sufficient. But, how can I ensure the statement (2) is sufficient?
Statement 2: p is the product of 5 consecutive positive integers.

If you take any five consecutive positive integers, you are sure to get minimum two EVEN positive integers. Since every even number is a multiple of 2, we get at least two 2s. Thus, p = Product of 5 consecutive positive integers is divisible by 4. Sufficient.

Example:

Case 1: Say the five consecutive positive integers are: 1, 2, 3, 4, 5. We see that the product of 2*4 = 8, thus, p = Product of 5 consecutive positive integers is divisible by 4.

Case 2: Say the five consecutive positive integers are: 17, 18, 19, 20, 21. We see that the product of 18*20 = 8*45, thus, p = Product of 5 consecutive positive integers is divisible by 4.

Hope this helps!

-Jay

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide
_________________
Manhattan Review GMAT Prep

Locations: New York | Vienna | Kuala Lumpur | Sydney | and many more...

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

GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Fri Oct 13, 2017 11:46 am
If you're multiplying five consecutive integers together, then at least two of them must be even. Since you've got at least two evens, you've got:

2*something * 2*something else =>

4*something*something else =>

a multiple of 4