It makes sense just intuitively. Since the numbers on each side have to match, any number added to it to make another palindrom would have to increase the number on each side by the same amount
Discussion
111 breaks that rule down and up right?
111-101=10
121-111=10
I didn’t say the difference of EVERY palindrome pair is a palindrome. Just that for every palindrome, there is a match (actually many) to result in another palindrome.
111+222=333
121+303=424