### Dhaka Junior 2011/5

Posted:

**Wed Feb 02, 2011 8:23 am**5. A

*palindrome*, such as $83438$, is a number that remains the same when its digits are reversed. How many four digit numbers are not palindromes?The Official Online Forum of BdMO

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Posted: **Wed Feb 02, 2011 8:23 am**

5. A *palindrome*, such as $83438$, is a number that remains the same when its digits are reversed. How many four digit numbers are not palindromes?

Posted: **Wed Feb 02, 2011 3:21 pm**

Four digit palindrome number should be like ABBA.If u reverse it u will get also ABBA.At first we will count how many numbers are palindrome.It is enough to count AB.SO we will get the result 9o.Then the ans 10000-90=9910

Posted: **Mon Dec 31, 2012 8:41 pm**

I did not get it. 9*9=81 should be palindromic numbers

Posted: **Mon Jan 14, 2013 8:02 pm**

4 digit number starts from 1000 soMehfuj Zahir wrote:Four digit palindrome number should be like ABBA.If u reverse it u will get also ABBA.At first we will count how many numbers are palindrome.It is enough to count AB.SO we will get the result 9o.Then the ans 10000-90=9910

there are 9000 4 digit numbers therefore the answer should be 8910

Posted: **Sat Nov 18, 2017 7:50 pm**

it will be 90

Posted: **Sat Nov 18, 2017 7:52 pm**

surjo wrote:I did not get it. 9*9=81 should be palindromic numbers

mate it will be 9 * 10