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

 It is currently 15 Jul 2018, 23:45

### 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

# How many odd three-digit integers greater than 800 are there

Author Message
VP
Joined: 21 Jul 2006
Posts: 1452
How many odd three-digit integers greater than 800 are there [#permalink]

### Show Tags

11 Nov 2008, 02:40
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

How many odd three-digit integers greater than 800 are there such that all their digits are different?

a) 40
b) 56
c) 72
d) 81
e) 104

Thanks

--== 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.
CEO
Joined: 17 Nov 2007
Posts: 3484
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Re: PS: How many odd three-digit integers [#permalink]

### Show Tags

11 Nov 2008, 02:59
1
C

1. Let's consider 8xy set
2. y e [1,3,5,7,9] (5 possibilities), x has 10 possibilities - 2 possibilities (8 and y). The total number is 5*8=40
3. Let's consider 9xy set
4. y e [1,3,5,7] (4 possibilities), x has 10 possibilities - 2 possibilities (9 and y). The total number is 4*8=32
5 40+32=72
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Director
Joined: 01 Aug 2008
Posts: 641
Re: PS: How many odd three-digit integers [#permalink]

### Show Tags

11 Nov 2008, 08:48
Walker,
great explanation. Thanks.
VP
Joined: 21 Jul 2006
Posts: 1452
Re: PS: How many odd three-digit integers [#permalink]

### Show Tags

12 Nov 2008, 03:56
walker wrote:
C

1. Let's consider 8xy set
2. y e [1,3,5,7,9] (5 possibilities), x has 10 possibilities - 2 possibilities (8 and y). The total number is 5*8=40
3. Let's consider 9xy set
4. y e [1,3,5,7] (4 possibilities), x has 10 possibilities - 2 possibilities (9 and y). The total number is 4*8=32
5 40+32=72

Great explanation walker! Thanks. The OA is C. I just have 1 question. Why did you have to start first from the left digit, then skipped the middle digit to go to the right digit, then back to the middle digit? Why couldn't you just go from left to middle, then from middle to right?

thanks
CEO
Joined: 17 Nov 2007
Posts: 3484
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Re: PS: How many odd three-digit integers [#permalink]

### Show Tags

12 Nov 2008, 04:13
I saw that we have two different cases here: 8 and 9. 9 is odd and we cannot choose 9 as a unit digit. 8 is even and don't add a restriction to a unit digit. That is why I started with division of the problem by two cases: 8xy and 9xy
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

VP
Joined: 21 Jul 2006
Posts: 1452
Re: PS: How many odd three-digit integers [#permalink]

### Show Tags

12 Nov 2008, 04:18
walker wrote:
I saw that we have two different cases here: 8 and 9. 9 is odd and we cannot choose 9 as a unit digit. 8 is even and don't add a restriction to a unit digit. That is why I started with division of the problem by two cases: 8xy and 9xy

as always, you never failed to answer my questions. you're a legend
thanks!

--== 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: PS: How many odd three-digit integers   [#permalink] 12 Nov 2008, 04:18
Display posts from previous: Sort by

# How many odd three-digit integers greater than 800 are there

Moderators: chetan2u, niks18, Bunuel, KarishmaB

# 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®.