Think of 3 digit palindromes as the 2 outer numbers (the same number)
and the inner number. There are 9 different sets of outer numbers
(think of 101, 202, 303, 404,…, 909), and 10 different possible inner numbers
(think of 101, 111, 121, 131, 141,…, 191). Multiply to get the total
number of 3 digit palindromes: 9 * 10 = 90 (C).