GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 17 Jul 2018, 14:33

### GMAT Club Daily Prep

#### 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

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

# remainder

Author Message
Current Student
Joined: 12 Jun 2008
Posts: 286
Schools: INSEAD Class of July '10

### Show Tags

25 Jul 2008, 01:10
nmohindru wrote:
rahulgoyal1986 wrote:
@ nmohindru

Frd

I cud not understand your approach. Kindly solve 4^24/7 for the remainder from your approach and post. Probably you have an easier and shorter way.

Rahul you are trying to compare apples with oranges

When divisor is 5 no matter what is tens digit the units digit always determine the remainder. In case of 7 this does not hold true so approach will be different.

Each number's specific properties regarding their squares, remainders etc are applied after seeing a particular Q and is only used to speed up that particular Q and should not be used to solve every Q of that nature.

Take a look at example below

If Q is whether 249678 is divisible by 11 then I would find sum of each even digit and compare with sum of each odd digit. If sum is equal that means number is divisible by 11. Now if Q is whether same number is divisible by 9 then I will sum each digit and see whether sum is divisible by 9 or not. So different approaches allow me to get the solution faster.

A consistent approach will be to divide the number and see which will give you correct answers for all the similar Qs.

Exactly why I said above :
Oski wrote:
The "unit digit repeats" method only works because the exercise asks to divide by 5. If it were by 4, 6, 7, etc... it wouldn't work.

That's why I think the "reminder repeats" method is better since it is a general method.

With the "remainder repeats" method, you can solve any of this problems, no need to bother with number divisibility properties (which don't exist for every numbers by the way )

But you were right in that if we want to divide by 5, looking at the unit digits is enough (but it is not the case if we divide by some other numbers)

Edit: Plus the question is not "IS Q = 249682 by 11?", but "what is the remainder of Q = 249682 when divided by 11?". When you are finished "finding sum of each even digit and comparing with sum of each odd digit" and when you see the difference is not divisible by 11 all you can say is that Q is not divisible by 11, but it won't give you the remainder
Senior Manager
Joined: 06 Apr 2008
Posts: 393

### Show Tags

25 Jul 2008, 01:33
Oski wrote:

Edit: Plus the question is not "IS Q = 249682 by 11?", but "what is the remainder of Q = 249682 when divided by 11?". When you are finished "finding sum of each even digit and comparing with sum of each odd digit" and when you see the difference is not divisible by 11 all you can say is that Q is not divisible by 11, but it won't give you the remainder

Off course ... cant use the method for finding remainder for 11
Manager
Joined: 27 May 2008
Posts: 137

### Show Tags

25 Jul 2008, 03:08
@ Oski & nmohindru

Thanks frds!! Oski has already written my response.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: remainder   [#permalink] 25 Jul 2008, 03:08

Go to page   Previous    1   2   [ 23 posts ]

Display posts from previous: Sort by

# remainder

Moderator: chetan2u

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.