Consider the number 28. It is not a palindrome. So, I reverse the number and
add it to itself (28+82 = 110). 110 is not a palindrome. So, I reverse it and add it
to itself (110 + 011 = 121). 121 is a palindrome. This means that 28 is a depth 2
palindrome (it took two iterations to make it a palindrome). What is the depth of
all two digit numbers?