Last visit was: 27 Apr 2026, 11:37 It is currently 27 Apr 2026, 11:37
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
User avatar
energetics
Joined: 05 Feb 2018
Last visit: 09 Oct 2020
Posts: 294
Own Kudos:
974
 [3]
Given Kudos: 325
Posts: 294
Kudos: 974
 [3]
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
User avatar
Jazzmin
Joined: 07 Jun 2018
Last visit: 20 Aug 2023
Posts: 41
Own Kudos:
212
 [2]
Given Kudos: 72
Location: United States
Posts: 41
Kudos: 212
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
DarkHorse2019
Joined: 29 Dec 2018
Last visit: 07 May 2020
Posts: 88
Own Kudos:
275
 [1]
Given Kudos: 10
Location: India
WE:Marketing (Real Estate)
Posts: 88
Kudos: 275
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Staphyk
Joined: 20 Mar 2018
Last visit: 30 Jan 2022
Posts: 467
Own Kudos:
376
 [2]
Given Kudos: 149
Location: Ghana
Concentration: Finance, Statistics
GMAT 1: 710 Q49 V39
Products:
GMAT 1: 710 Q49 V39
Posts: 467
Kudos: 376
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
How many different three-digit integers have exactly three different digits?

Let the number =abc; Notice that a cant take digit 0 as it’s a three-digit number. Digit can’t be reused

Now a has 9 possibilities , b has 9 possibilities as we can’t reuse any digit, lastly c has 8 possibilities

.: Number of different three digit integer = 9•9•8 = 81•8 = 648

Smack that B! :)

Posted from my mobile device
User avatar
freedom128
Joined: 30 Sep 2017
Last visit: 01 Oct 2020
Posts: 939
Own Kudos:
1,377
 [3]
Given Kudos: 402
GMAT 1: 720 Q49 V40
GPA: 3.8
Products:
GMAT 1: 720 Q49 V40
Posts: 939
Kudos: 1,377
 [3]
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Rohanborude,

Let the number be XYZ;

X has 9 possibilities (0 is not allowed).
Y has 9 possibilities (number in X cannot be repeated).
Z has 8 possibilities (numbers in both X and Y cannot be repeated).

Number of different three digit integer = 9*9*8 = 648. Answer is (B)

Smack that +1 kudo below if you like my explanation

Posted from my mobile device
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 27 Apr 2026
Posts: 5,988
Own Kudos:
Given Kudos: 163
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
GMAT 1: 690 Q50 V34
Posts: 5,988
Kudos: 5,860
Kudos
Add Kudos
Bookmarks
Bookmark this Post
DarkHorse2019
How many different three-digit integers have exactly three different digits?

(A) 504
(B) 648
(C) 720
(D) 891
(E) 1,000

Source: Math Bible (Jeff Sacksmann)

Asked: How many different three-digit integers have exactly three different digits?

For hundred digit, number of choices = 9
For tenth digit, number of choices = 9 (can not use hundred digit again)
For units digit, number of choices =8. (can not use hundred and tenth digits again)

Number of different 3 digit integers = 9*9*8 = 648


IMO B
User avatar
exc4libur
Joined: 24 Nov 2016
Last visit: 22 Mar 2022
Posts: 1,680
Own Kudos:
Given Kudos: 607
Location: United States
Posts: 1,680
Kudos: 1,469
Kudos
Add Kudos
Bookmarks
Bookmark this Post
DarkHorse2019
How many different three-digit integers have exactly three different digits?

(A) 504
(B) 648
(C) 720
(D) 891
(E) 1,000

Source: Math Bible (Jeff Sacksmann)

given: there are total of 10 digits (0,1,2,3,4,5,6,7,8,9)

thousands: 9 choices (because you can't have 0)
hundreds: 9 choices (10-1=9 digits left, since we used a digit for the thousands)
units: 8 choices (10-2=8 digits left, since we used a digit for the thousands and another for the hundreds)
total three-digit integers with different digits: 9*9*8=81*8=648

Answer (B).
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 27 Apr 2026
Posts: 109,928
Own Kudos:
Given Kudos: 105,914
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,928
Kudos: 811,594
Kudos
Add Kudos
Bookmarks
Bookmark this Post
DarkHorse2019
How many different three-digit integers have exactly three different digits?

(A) 504
(B) 648
(C) 720
(D) 891
(E) 1,000

Source: Math Bible (Jeff Sacksmann)

Merging topics. Please search before posting. Thank you.
User avatar
Archit3110
User avatar
Major Poster
Joined: 18 Aug 2017
Last visit: 27 Apr 2026
Posts: 8,633
Own Kudos:
Given Kudos: 243
Status:You learn more from failure than from success.
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1: 545 Q79 V79 DI73
GMAT Focus 2: 645 Q83 V82 DI81
GPA: 4
WE:Marketing (Energy)
Products:
GMAT Focus 2: 645 Q83 V82 DI81
Posts: 8,633
Kudos: 5,191
Kudos
Add Kudos
Bookmarks
Bookmark this Post
first digit = 9
second digit = 9 ' 0' also possible
third digit ; 8
9*9*8 ; 648
IMO B

energetics
How many different three-digit integers have exactly three different digits?

(A) 504
(B) 648
(C) 720
(D) 891
(E) 1,000

I'm wondering if the way I did it makes sense...
1) Ignoring the restriction that 0 can't be in the first position: 10P3 = 10*9*8 = 720
2) Remove the possibilities with 0 in the first position (1/10th the total of 10P3): 720/10 = 72
3) Subtract the possibilities with 0 in first position from total: 720 - 72 = 648

Explanation:
There are nine different possibilities for the first digit: anything between 1 and 9. The tricky part of this question is moving to the second digit. Again, there are nine possibilities for the second digit: any number between 0 and 9, not including the one using for the first digit. Remember, a three-digit number can have zero as a digit, just not as the first digit. Finally, the third digit has eight possibilities: anything between 0 and 9 except for the two digits used already. The number of possible integers, then, is: 9 × 9 × 8 = 648, choice (B).
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,987
Own Kudos:
Posts: 38,987
Kudos: 1,119
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Math Expert
109928 posts
Tuck School Moderator
852 posts