It is currently 22 Sep 2017, 03:07

Close

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
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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is a 3-digit integer divisible by 3?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

1 KUDOS received
Intern
Intern
avatar
Joined: 10 Aug 2010
Posts: 6

Kudos [?]: 18 [1], given: 0

Is a 3-digit integer divisible by 3? [#permalink]

Show Tags

New post 10 Aug 2010, 05:48
1
This post received
KUDOS
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

72% (00:46) correct 28% (00:33) wrong based on 43 sessions

HideShow timer Statistics

Is a 3-digit integer divisible by 3?

(1) The hundreds' digit of the number is equal to the tens' digit of the number.
(2) The units' digit of the number is 6 greater than the tens' digit of the number


[Reveal] Spoiler:
A little confused

I'll start by naming the integers A B C

(1) if 100's digit is = 10's digit then A = B so it now becomes A A C unit place is not given so INSUFF

(2) if unit digit is 6 greater than the 10's digit the number will read as A B 6+B since 100's digit is not given it still is INSUFF (to me)

BOTH together then it will read something like this A A 6+A

so the numbers will be either 116 , 227 or 339 to me it is still INSUFF and i picked E

where am i going wrong ??

Sorry about posting in such a short time My exam is very very close!!!!
[Reveal] Spoiler: OA

Kudos [?]: 18 [1], given: 0

Expert Post
1 KUDOS received
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 41682

Kudos [?]: 124394 [1], given: 12078

Re: Is a 3-digit integer divisible by 3? [#permalink]

Show Tags

New post 10 Aug 2010, 06:23
1
This post received
KUDOS
Expert's post
amijags wrote:
Is a 3-digit integer divisible by 3?
(1) The hundreds' digit of the number is equal to the tens' digit of the number.
(2) The units' digit of the number is 6 greater than the tens' digit of the number


OA
[Reveal] Spoiler:
C


A little confused

I'll start by naming the integers A B C

(1) if 100's digit is = 10's digit then A = B so it now becomes A A C unit place is not given so INSUFF

(2) if unit digit is 6 greater than the 10's digit the number will read as A B 6+B since 100's digit is not given it still is INSUFF (to me)

BOTH together then it will read something like this A A 6+A

so the numbers will be either 116 , 227 or 339 to me it is still INSUFF and i picked E

where am i going wrong ??

Sorry about posting in such a short time My exam is very very close!!!!


First # should be 117, which is divisible by 3 and second number should be 228, which is also divisible by 3. So all 3 numbers possible: 117, 228 and 339 are divisible by 3.

Is a 3-digit integer divisible by 3?

Algebraic solution:

A number is divisible by 3 if the sum of its digits is divisible by 3. So 3-digit integer \(abc\) will be divisible by 3 if \(a+b+c=3k\), where k is integer or to make it simpler if \(a+b+c\) is a multiple of 3.

(1) The hundreds' digit of the number is equal to the tens' digit of the number --> \(a=b\) --> \(a+b+c=b+b+c=2b+c\). Now, \(2b+c\) may or may not be a multiple of 3, hence this statement is insufficient.

(2) The units' digit of the number is 6 greater than the tens' digit of the number --> \(c=b+6\) --> \(a+b+c=a+b+b+6=a+2b+6\). Now, \(a+2b+6\) may or may not be a multiple of 3, hence this statement is insufficient.

(1)+(2) As from (1) \(a=b\) and from (2) \(c=b+6\) then \(a+b+c=b+b+b+6=3b+6=3(b+2)\). As \(3(b+2)\) has 3 as multiple hence it's divisible by 3. Sufficient.

Answer: C.


!
Please post PS questions in the PS subforum: gmat-problem-solving-ps-140/
Please post DS questions in the DS subforum: gmat-data-sufficiency-ds-141/

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 124394 [1], given: 12078

Intern
Intern
avatar
Joined: 10 Aug 2010
Posts: 6

Kudos [?]: 18 [0], given: 0

Re: Is a 3-digit integer divisible by 3? [#permalink]

Show Tags

New post 10 Aug 2010, 06:36
OMG i cant believe i made this stupid mistake!!!!!!! shame on me

Kudos [?]: 18 [0], given: 0

1 KUDOS received
Manager
Manager
avatar
Joined: 03 Jun 2010
Posts: 173

Kudos [?]: 70 [1], given: 40

Location: United States (MI)
Concentration: Marketing, General Management
WE: Business Development (Consumer Products)
GMAT ToolKit User Reviews Badge
Re: Is a 3-digit integer divisible by 3? [#permalink]

Show Tags

New post 10 Aug 2010, 08:21
1
This post received
KUDOS
we have 100a+10b+c
from (1) we have a=b, thus
100a+10a+с
from (2) we have c=6+a, so
100a+10a+a+6 = 111a+6
plug any figure instead of a, you will see it divisible by 3.
(C)

Kudos [?]: 70 [1], given: 40

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 17594

Kudos [?]: 270 [0], given: 0

Premium Member
Re: Is a 3-digit integer divisible by 3? [#permalink]

Show Tags

New post 14 Aug 2017, 03:07
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.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Kudos [?]: 270 [0], given: 0

Re: Is a 3-digit integer divisible by 3?   [#permalink] 14 Aug 2017, 03:07
    Similar topics Author Replies Last post
Similar
Topics:
2 X is a 4-digit integer, and Y is a 3-digit integer. Is the sum of the SajjadAhmad 2 01 May 2017, 21:41
1 EXPERTS_POSTS_IN_THIS_TOPIC Is 3-digit integer n a prime number? MathRevolution 2 14 May 2017, 18:32
2 EXPERTS_POSTS_IN_THIS_TOPIC If a is a 3-digit integer and b is a 3-digit integer, is the units Bunuel 5 08 Aug 2017, 08:55
11 EXPERTS_POSTS_IN_THIS_TOPIC When 3-digit integer 6a3 plus 3-digit integer 3b5 is divisible by 9, i MathRevolution 6 13 Nov 2016, 11:48
EXPERTS_POSTS_IN_THIS_TOPIC If 2ab is a 3 digit integer, is 2ab divisible by 3? MathRevolution 6 29 Sep 2016, 06:33
Display posts from previous: Sort by

Is a 3-digit integer divisible by 3?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.