GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 28 Mar 2020, 22:50

### 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

# A palindrome is a number that reads the same forward and backward.

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

### Hide Tags

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3318
A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

Updated on: 21 Jul 2018, 03:53
1
6
00:00

Difficulty:

25% (medium)

Question Stats:

68% (00:52) correct 32% (01:14) wrong based on 140 sessions

### HideShow timer Statistics

Permutation and Combination - Practice Question #2

2-A palindrome is a number that reads the same forward and backward. For example, 1221 and 232 are palindromes. By using the numbers from 0-9, how many 5-digit palindromes can be created.

Options

a) 648
b) 729
c) 800
d) 900
e) 1000

To solve Question 1: Question 1

To solve Question 3: Question 3

To read our article: Must Read Articles and Practice Questions to score Q51 !!!!

_________________

Originally posted by EgmatQuantExpert on 20 Jul 2018, 04:24.
Last edited by chetan2u on 21 Jul 2018, 03:53, edited 3 times in total.
Shifted the topic from DS to PS
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3318
A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

Updated on: 16 Dec 2018, 10:04

Solution

Given:
• A palindrome is a number that reads the same forward and backward.

To find:
• By using the numbers from 1-9, how many 5-digit palindromes can be created

Approach and Working:

Let the 5-digit number is abcba.

So, we need to find the in how many we can fill a, b, and c since the last two digits will take the same number.
• a can take 9 numbers from 1-9.
• b can take 10 numbers from 0-9.
• c can take 10 numbers from 0-9.

Thus, way to form a 5-digit palindrome number= 9 * 10 * 10 *1 *1= 900.

Hence, the correct answer is option D.

_________________

Originally posted by EgmatQuantExpert on 20 Jul 2018, 04:27.
Last edited by EgmatQuantExpert on 16 Dec 2018, 10:04, edited 6 times in total.
Manager
Joined: 05 Feb 2016
Posts: 164
Location: India
Concentration: General Management, Marketing
WE: Information Technology (Computer Software)
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

Updated on: 20 Jul 2018, 06:30
EgmatQuantExpert wrote:
Permutation and Combination - Practice Question #2

2-A palindrome is a number that reads the same forward and backward. For example, 1221 and 232 are palindromes. By using the numbers from 0-9, how many 5-digit palindromes can be created.

Options

a) 648
b) 729
c) 800
d) 900
e) 1000

To read our article: Must Read Articles and Practice Questions to score Q51 !!!!

I am getting 5 arrangements

ABCBA- Total arrangement A(10)*B(9)*C(8)=720 , A can be selected in 10,b in 9 and C in 8 ways
ABBBA- Total arrangement A(10)*B(9)=90
ABABA-Total arrangement A(10)*B(9)=90
AAAAA- Total arrangement A(10)=10
ABBBA-Total arrangement A(10)*B(9)=90

Total=720 +90+90+90+10=1000
Considering 0 also since its not telling 5 digit number . correct me if i am wrong

Originally posted by kunalcvrce on 20 Jul 2018, 05:28.
Last edited by kunalcvrce on 20 Jul 2018, 06:30, edited 1 time in total.
Intern
Joined: 30 Apr 2017
Posts: 6
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

20 Jul 2018, 05:57
900?

- - - - - 5 places to filled. 1 blank can be filled in 9 ways.(1-9) last blank in 1 way as it has to be the same number as the 1 blanck. 2 blank can be filled in 10 ways (0-9). similarly 4 blank can be filled in 1 way only. lastly the 3 blank can also be filled in 10 ways
so 9*10*10=900
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3318
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

20 Jul 2018, 22:03
Manager
Joined: 22 Jan 2014
Posts: 165
WE: Project Management (Computer Hardware)
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

21 Jul 2018, 03:06
EgmatQuantExpert wrote:
Permutation and Combination - Practice Question #2

2-A palindrome is a number that reads the same forward and backward. For example, 1221 and 232 are palindromes. By using the numbers from 0-9, how many 5-digit palindromes can be created.

Options

a) 648
b) 729
c) 800
d) 900
e) 1000

To solve Question 1: Question 1

To solve Question 3: Question 3

To read our article: Must Read Articles and Practice Questions to score Q51 !!!!

Number is of the form abcde
a can be filled in 9 ways (1-9)
b can be filled in 10 ways (0-9)
c can be filled in 10 ways (0-9)
d=b, so 1 way
e=a, so 1 way
total = 9*10*10*1*1 = 900
_________________
Illegitimi non carborundum.
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3318
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

23 Jul 2018, 04:57
Senior SC Moderator
Joined: 22 May 2016
Posts: 3660
A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

15 Dec 2018, 10:12
EgmatQuantExpert wrote:

Solution

Given:
• A palindrome is a number that reads the same forward and backward.

To find:
• By using the numbers from 1-9, how many 5-digit palindromes can be created

Approach and Working:

Let the 5-digit number is abcba.

So, we need to find the in how many we can fill a, b, and c since the last two digits will take the same number.
• a can take 9 numbers from 1-9.
• b can take 10 numbers from 0-9.
• c can take 10 numbers from 0-9.

Thus, way to form a 5-digit palindrome number= 9 * 10 * 10 *1 *1= 729.

Hence, the correct answer is option D.

EgmatQuantExpert , a couple of items are inconsistent.

It appears that Question #2:
1) ought to list 0-9 as the digits that are available in both topic threads (the solution prompt needs to be edited to match original);
2) ought to have a calculation error corrected.

Issues
(1) 0-9 or 1-9?
In the original prompt for Q #2, the available digits are integers 0-9. In the solution prompt (please see highlights above), both (1-9) and (0-9) are listed.

The original prompt for Question #2 that lists 0-9 is HERE
Quote:
By using the numbers from 0-9, how many 5-digit palindromes can be created.

(2) the second post on Q#2 solution has a calculation error, although the OA is listed correctly.
Quote:
Thus, way to form a 5-digit palindrome number= 9 * 10 * 10 *1 *1= 729.

(9 * 10 * 10 * 1 * 1) = 900, not 729.

It appears that Questions #1 and #2 got mixed up. The answer to Question 1 HERE, (answer is HERE) is 729.
In Question #1, the digits are limited to 1-9.

I think Q#2
-- needs to state that integers are 0-9 in all posts and
-- needs to have the written answer changed to 900

Would you please correct the inconsistencies?
_________________
Visit SC Butler, here! Get two SC questions to practice, whose links you can find by date.

Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has. -- Margaret Mead
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 6057
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

16 Dec 2018, 00:10
EgmatQuantExpert :

Thus, way to form a 5-digit palindrome number= 9 * 10 * 10 *1 *1= 729.

it should be 900 not 729..

EgmatQuantExpert wrote:

Solution

Given:
• A palindrome is a number that reads the same forward and backward.

To find:
• By using the numbers from 1-9, how many 5-digit palindromes can be created

Approach and Working:

Let the 5-digit number is abcba.

So, we need to find the in how many we can fill a, b, and c since the last two digits will take the same number.
• a can take 9 numbers from 1-9.
• b can take 10 numbers from 0-9.
• c can take 10 numbers from 0-9.

Thus, way to form a 5-digit palindrome number= 9 * 10 * 10 *1 *1= 729.

Hence, the correct answer is option D.

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3318
Re: A palindrome is a number that reads the same forward and backward.  [#permalink]

### Show Tags

16 Dec 2018, 10:05
Re: A palindrome is a number that reads the same forward and backward.   [#permalink] 16 Dec 2018, 10:05
Display posts from previous: Sort by

# A palindrome is a number that reads the same forward and backward.

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

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne