2 digit Palindrome describes a process by which most multi-digit numbers eventually become palindromes. The process being to repeatedly add a given number to the number formed when its digits are reversed.
For example: 152 -> 152+251=403 -> 403+304=707

I applied that process to a certain three digit number four times before I got a palindrome.
After the first and second additions, it was still a three digit number, and neither was a palindrome.
After the third addition it became a four digit number, but still not a palindrome.
And after the fourth addition the result was a four digit palindrome.

What number did I start with, assuming the first digit was smaller than the last?

The number stated with was 192.

  192 <-- first digit, 1, is less than last digit, 2
+ 291
  483 <-- after 1st addition, 3 digit non-palindrome
+ 384
  867 <-- after 2nd addition, 3 digit non-palindrome
+ 768     
 1635 <-- after 3rd addition, 4 digit non-palindrome
+5361
 6996 <-- after 4th addition, 4 digit palindrome!

Posted by Dej Mar on 2009-11-27 19:24:10