Last visit was: 06 Jun 2026, 17:21 It is currently 06 Jun 2026, 17:21
Home
Messages
MBA Fair
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
User avatar
madcowudub
User avatar
Joined: 02 Mar 2007
Last visit: 18 Aug 2008
Posts: 21
Own Kudos:
3
Posts: 21
Kudos: 3
OG question. 17 Jul 2007, 02:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
This a question in the OG.

Of the three-digit integers greather than 700, how many have two digits that are equal to each other and the remaining digit different from the other two?

a. 90
b. 82
c. 80
d. 45
e. 36

i see the answer and explanation in the OG but still don't understand. please help. thanks



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
User avatar
GK_Gmat
User avatar
Joined: 09 Aug 2006
Last visit: 28 Feb 2009
Posts: 348
Own Kudos:
1,081
Posts: 348
Kudos: 1,081
OG question. 17 Jul 2007, 02:52
Kudos
Add Kudos
Bookmarks
Bookmark this Post
madcowudub
This a question in the OG.

Of the three-digit integers greather than 700, how many have two digits that are equal to each other and the remaining digit different from the other two?

a. 90
b. 82
c. 80
d. 45
e. 36

i see the answer and explanation in the OG but still don't understand. please help. thanks
Show more


Counting the numbers greater than 700 and less than 800, that have 2 digits that are equal and one digit different, I get 17.

We can multiply 17 by 3 (for 700, 800 and 900) to get the digits greater than 700 and less than 1000 with 2 digits that are equal and one digit different to give us 51. Since we haven't counted the numbers 800 and 900 (which have two 0's same and one digit different) we need to add 2 to 51 to get an answer of 53.

This is not even in the answer choices!! So obviously I'm going very wrong somewhere.
User avatar
[email protected]
User avatar
Joined: 14 Jan 2007
Last visit: 04 Feb 2009
Posts: 312
Own Kudos:
958
Posts: 312
Kudos: 958
OG question. 17 Jul 2007, 02:52
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Is it 80.

If correct, I will explain.
User avatar
Finding Perdition
User avatar
Joined: 05 Mar 2007
Last visit: 27 Jul 2008
Posts: 81
Own Kudos:
8
Posts: 81
Kudos: 8
OG question. 17 Jul 2007, 03:08
Kudos
Add Kudos
Bookmarks
Bookmark this Post
[email protected]
Is it 80.

If correct, I will explain.
Show more


How did you get 80?

FP
User avatar
[email protected]
User avatar
Joined: 14 Jan 2007
Last visit: 04 Feb 2009
Posts: 312
Own Kudos:
958
Posts: 312
Kudos: 958
OG question. 17 Jul 2007, 03:20
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Finding Perdition
[email protected]
Is it 80.

If correct, I will explain.

How did you get 80?

FP
Show more


First we count the numbers with the pattern, 77x , 88x and 99x .
Such numbers will be 9+9+9 = 27

Count the numbers with the pattern, 7x7 , 8x8 and 9x9 .
Such numbers will be 9+9+9 = 27

Count the numbers with pattern 7xx, 8xx and 9xx
Such numbers will be 8+8+8 = 24

Add two more numbers 700 and 800.
So numbers = 27+27+24+2 = 80
User avatar
madcowudub
User avatar
Joined: 02 Mar 2007
Last visit: 18 Aug 2008
Posts: 21
Own Kudos:
3
Posts: 21
Kudos: 3
OG question. 17 Jul 2007, 06:56
Kudos
Add Kudos
Bookmarks
Bookmark this Post
great reply! much better than the OG reply....is there any other way that would be faster than counting? such as using (numbers 701-999)-(numbers that don't contain two 7s)?
User avatar
dahcrap
User avatar
Joined: 03 Jun 2007
Last visit: 27 May 2008
Posts: 159
Own Kudos:
33
 [1]
Posts: 159
Kudos: 33
 [1]
OG question. 17 Jul 2007, 10:30
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Let me try a faster way

Lets find 7xx. We get 9 ways. So 8xx and 9xx will have 9 ways each so 27
Remember x is not equal to 7, 8, 9 respectively

Lets find 77x We get 9 ways. Similary 88x and 99x so total is 27
Remember x is not equal to 7, 8, 9 respectively

Let find 7x7. We get 9 Similarly for 8x8 and 9x9. we get total of 27
Remember x is not equal to 7, 8, 9 respectively

Now rememeber to do away with 700 in step as the stem says > 700.

So it is 81-1 = 80



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!