Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: What is the remainder when x^2 - y^2 is divided by 3? [#permalink]

Show Tags

01 Nov 2013, 03:02

Bunuel wrote:

What is the remainder when x^2 - y^2 is divided by 3?

(1) x^2 is divisible by 6. No info about y. Not sufficient. (2) y^2 is divisible by 9. No info about y. Not sufficient.

(1)+(2) x^2 - y^2 = (multiple of 3) - (multiple of 3) = (multiple of 3), thus the remainder is zero. Sufficient.

Answer: C.

Why do we need information about y for 2)? Don't we need information about x^2 to determine the answer in (2)? (x^2 - y^2)%3 = ((x^2)%3-(y^2)%3)%3 1) (0 - (y^2)%3)%3 = -(y^2)%3 | NS 2)((x^2)%3-0)%3 = (x^2)%3 | NS (1)+(2): 0

Last edited by TooLong150 on 02 Nov 2013, 05:31, edited 1 time in total.

Re: What is the remainder when x^2 - y^2 is divided by 3? [#permalink]

Show Tags

01 Nov 2013, 22:58

Official Explantion

Answer: C - Each of the statements are insufficient on their own; we're looking for something concerning an expression with two variables, and each statement concerns only one of the variables.

Taken together, the statements are sufficient. If x^2 is divisible by 6, it is also divisible by all the factors of 6, including 3. The same reasoning applies to y^2. Since both x^2 and y^2 are divisible by 3, the difference between them is also divisible by 3, so the remainder is 0. Choice (C) is correct.

Re: What is the remainder when x^2 - y^2 is divided by 3? [#permalink]

Show Tags

25 Feb 2016, 06:31

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Re: What is the remainder when x^2 - y^2 is divided by 3? [#permalink]

Show Tags

22 Mar 2016, 06:59

Here is the rule that is quite helpful in problems such as these for any integer X= 5p+2 and X=3P+2 the general expression for X becomes => X = 2+15P as 15 is the LCM of 3 and 5
_________________

Give me a hell yeah ...!!!!!

gmatclubot

Re: What is the remainder when x^2 - y^2 is divided by 3?
[#permalink]
22 Mar 2016, 06:59

[rss2posts title=The MBA Manual title_url=https://mbamanual.com/2016/11/22/mba-vs-mim-guest-post/ sub_title=MBA vs. MiM :3qa61fk6]Hey, guys! We have a great guest post by Abhyank Srinet of MiM-Essay . In a quick post and an...

[rss2posts title=The MBA Manual title_url=https://mbamanual.com/2016/11/21/mba-vs-mim-guest-post/ sub_title=MBA vs. MiM :2kn54ay1]Hey, guys! We have a great guest post by Abhyank Srinet of MiM-Essay . In a quick post and an...

Marketing is one of those functions, that if done successfully, requires a little bit of everything. In other words, it is highly cross-functional and requires a lot of different...