For every choice of the _three first_ digits of a 5-digit number, there is exactly one way to complete it so it becomes a palindrome.
The next palindrome is the one that starts with 730, namely 73037, which will be reached in $73037-72927=110$ km.
For every choice of the _three first_ digits of a 5-digit number, there is exactly one way to complete it so it becomes a palindrome.
The next palindrome is the one that starts with 730, namely 73037, which will be reached in $73037-72927=110$ km.