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:

To find if number x is divisible by: 2: If x is even, True 3: If the sum of the digits of x are a multiple of 3, True 4: If the ones and tens digits form a number that is divisible by 4, True 5: If the ones digit is a 0 or 5, True 6: If x is divisible by 2 AND 3, True 7: Double the ones digit and subtract the last number from the remaining digits. If difference divisible by 7, True 8: If last 3 digits form a number that is divisible by 8, True OR If x is divisible by 2 three times, True 9: If the sum of the digits are a multiple of 9, True 10: If the ones digit is 0, True 11 (Method 1): Add each digit using these properties: - + - +... If the resulting number is divisible by 11, True 11 (Method 2): Starting with ones digit, add every other number (A). Add the remaining numbers (B). If A - B is divisible by 11, True 12: If sum of the digits is a multiple of 3 and the last two digits are a multiple of 4, True 15: If x is divisible by 3 AND 5, True

4 Example: Is 312 divisible by 4? If the ones and tens digits form a number that is divisible by 4 then true. The ones and tens digits form 12 and 12 is divisible by 4, therefore true.

7 Example: Is 357 divisible by 7? Double the ones digit (7) to get 14. Subtract 14 from remaining digits (35) to get 21. 21 is divisible by 7, therefore true.

9 Example: Is 95,301 divisible by 9? The number 95,301 is divisible by 9 because the digits add to 18 (9+5+3+0+1), which is a multiple of 9.

11 (Method 1) Example: Is 824,472 divisible by 11? -8 + 2 - 4 + 4 - 7 + 2 = -11, which is divisible by 11, therefore 824,472 is divisible by 11.

11 (Method 2) Example: Is 824,472 divisible by 11? Starting with the units digit, add every other number:2 + 4 + 2 = 8. Then add the remaining numbers: 7 + 4 + 8 = 19. Since the difference between these two sums is 11, which is divisible by 11, 824472 is divisible by 11.

If anyone knows any other divisible number properties, please list them. Thanks.

Last edited by I3igDmsu on 28 Feb 2010, 19:30, edited 15 times in total.

There's no reason to exclude 0. Zero is definitely divisible by 2;

I3igDmsu wrote:

4: If the ones and tens digits of x are divisible by 4, True

You mean: if the tens and ones digits form a number which is divisible by 4. The number 31,212 is divisible by 4, for example, because the last two digits form a number (12) which is divisible by 4, even though the tens digit and the ones digit are not individually divisible by 4.

I3igDmsu wrote:

5: If the ones digit is a 0 or 5, True (excludes x = 0)

There's no reason to exclude 0. Zero is definitely divisible by 5;

I3igDmsu wrote:

8: If last 3 digits are divisible by 8, True OR If x is divisible by 2 three times, True

Again for clarity - the last three digits should form a number divisible by 8. For example, 85,328 is divisible by 8 because 328 is divisible by 8 (328 = 8*41).

I3igDmsu wrote:

9: If the sum of the digits are 9, True

You mean: If the sum of the digits is a multiple of 9. The sum does not need to equal 9. The number 95,301 is divisible by 9, for example, because the digits add to 18, which is a multiple of 9.

I3igDmsu wrote:

10: If the ones digit is 0, True (excludes x=0)

There's no reason to exclude 0. Zero is definitely divisible by 10;
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

11 Example: Is 824,472 divisible by 11? Starting with the units digit, add every other number:2 + 4 + 2 = 8. Then add the remaining numbers: 7 + 4 + 8 = 19. Since the difference between these two sums is 11, which is divisible by 11, 824472 is divisible by 11.

If anyone knows any other divisible number properties, please list them. Thanks.

Ok there's maybe one little simplification for the divisibility of number 11:

There's one scheme applied to the digits : - + - + etc. if the forming number is divisible by 11 then our number is divisible by 11.

Lets take for ex 3916 which is divisible by 11. Application : -3 + 9 - 1 + 6 = 11 -----> so 3916 is divisible by 11.

Another example. 1099989

-1+0-9+9-9+8-9 = -11 --------. so 1099989 is divisible by 11.

7: Double the ones digit and subtract the last number from the remaining digits. If difference divisible by 7, True

I cannot for the life of me figure out how this works. Would anybody be kind enough to break this methodology down with a specific example so I can see what I'm doing wrong?

Bah my post got deleted. Thanks for the table. By the way, on page 244 Kaplan Premier they—incorrectly—state that, "...you can combine these rules above with factorization tom figure out whether a number is divisible by other numbers." the example given is that 8184 is divisible by 44 because it is divisible by (4 and 11). While this may be true in this case, it should advise that you use prime factorization.

For example, 36 is divisible by both 4 and 2, yet it is not divisible by 8. Rather, it should be divisible by 2 three times.

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.
_________________

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.
_________________

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.
_________________

Version 8.1 of the WordPress for Android app is now available, with some great enhancements to publishing: background media uploading. Adding images to a post or page? Now...

Post today is short and sweet for my MBA batchmates! We survived Foundations term, and tomorrow's the start of our Term 1! I'm sharing my pre-MBA notes...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...