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A palindrome is a number that reads the same forward and backward.
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Updated on: 20 Jul 2018, 23:11
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Permutation and Combination  Practice Question #11A palindrome is a number that reads the same forward and backward. For example, 1221 and 232 are palindromes. By using the numbers from 19, how many 5digit palindromes can be created. Options a) 648 b) 729 c) 800 d) 900 e) 1000 To solve Question 2: Question 2To solve Question 3: Question 3To read our article: Must Read Articles and Practice Questions to score Q51 !!!!
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A palindrome is a number that reads the same forward and backward.
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Updated on: 23 Jul 2018, 05:44
Solution Given:• A palindrome is a number that reads the same forward and backward. To find:• By using the numbers from 19, how many 5digit palindromes can be created
Approach and Working: Let the 5digit 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 19. • b can take 9 numbers from 19. • c can take 9 numbers from 19. Thus, way to form a 5digit palindrome number= 9 * 9 * 9 *1 *1= 729. Hence, the correct answer is option B. Answer: B
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Re: A palindrome is a number that reads the same forward and backward.
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20 Jul 2018, 06:20
EgmatQuantExpert wrote: Permutation and Combination  Practice Question #11A palindrome is a number that reads the same forward and backward. For example, 1221 and 232 are palindromes. By using the numbers from 19, how many 5digit 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(9)*B(8)*C(7)=504 , A can be selected in 9,b in 8 and C in 7 ways ABBBA Total arrangement A(9)*B(8)=72 ABABA Total arrangement A(9)*B(8)=72 AAAAA Total arrangement A(9)=9 ABBBA Total arrangement A(9)*B(8)=72 Total= 504+72+72+72+9=729



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Re: A palindrome is a number that reads the same forward and backward.
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20 Jul 2018, 10:44
Since , there are total 5 digits.We need to worry about just 3 digits . _ _ _ _ _ 9 9 9 1 1 hence , total =9*9*9=729



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Re: A palindrome is a number that reads the same forward and backward.
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20 Jul 2018, 23:26



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Re: A palindrome is a number that reads the same forward and backward.
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20 Jul 2018, 23:28
Yes..I sure want to try Sent from my iPhone using GMAT Club Forum mobile app



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Re: A palindrome is a number that reads the same forward and backward.
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20 Jul 2018, 23:30
EgmatQuantExpert wrote: Hey kunalcvrce, Your answer is correct. But, this question can be done very quickly. Do you want to give another try? Regards, Ashutosh eGMAT EgmatQuantExpert Aditya has answered in better way ..above Sent from my iPhone using GMAT Club Forum mobile app



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Re: A palindrome is a number that reads the same forward and backward.
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21 Jul 2018, 01:50
Why it should not be 9*9*8 or 9*10*10 (Repetetion of digits allowed)?



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Re: A palindrome is a number that reads the same forward and backward.
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21 Jul 2018, 02:31
EgmatQuantExpert wrote: Hey kunalcvrce, Your answer is correct. But, this question can be done very quickly. Do you want to give another try? Regards, Ashutosh eGMATPalindrome = xyzyx X,Y, Z each can take 9 values 9x9x9= 729



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Re: A palindrome is a number that reads the same forward and backward.
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21 Jul 2018, 09:21
The 5 digit palindrome has to be as simple as XYZYX, i.e. consist of only 3 numbers.
X can be selected in 9 ways Y can be selected in 9 ways Z can be selected in 9 ways
So, total palindroms would be 9X9X9 = 729



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Re: A palindrome is a number that reads the same forward and backward.
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21 Jul 2018, 09:34
Shouldn't it be 900?
1st digit : 9 ways (19) 2nd digit: 10 ways (09) 3rd digit: 10 ways (09) 4th digit : 1 way 5th digit : 1 way
Any clarification will be appreciated!



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Re: A palindrome is a number that reads the same forward and backward.
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21 Jul 2018, 09:36
greenisthecolor wrote: Shouldn't it be 900?
1st digit : 9 ways (19) 2nd digit: 10 ways (09) 3rd digit: 10 ways (09) 4th digit : 1 way 5th digit : 1 way
Any clarification will be appreciated! Hi greenisthecolorThe digits are from 19 so 10 ways not possible Sent from my iPhone using GMAT Club Forum mobile app



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A palindrome is a number that reads the same forward and backward.
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21 Jul 2018, 09:57
kunalcvrce wrote: greenisthecolor wrote: Shouldn't it be 900?
1st digit : 9 ways (19) 2nd digit: 10 ways (09) 3rd digit: 10 ways (09) 4th digit : 1 way 5th digit : 1 way
Any clarification will be appreciated! The digits are from 19 so 10 ways not possible Oh yeah. Silly me. I am doing similar mistakes more often than i'd like to. Thanks!



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Re: A palindrome is a number that reads the same forward and backward.
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23 Jul 2018, 05:56




Re: A palindrome is a number that reads the same forward and backward. &nbs
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