A new December and a new bunch of puzzles from mscroggs.co.uk.

The candidate numbers all have 2 digits, ab. A palindrome number of this kind has a = b. So the palindrome numbers are 11, 22, …, 99.

11 + 22 + … + 99 =

(1+2+…+9)*11 =

9*5*11 =

495