A2. A palindromic number is a number that reads the same from left to right as it does from right to left, such as 707 and 154451. Leon is making a list of all five-digit palindromic numbers (numbers do not start with a 0), sorted from smallest to largest.

What is the 12th number on Leon's list?
A) 11111
B) 11211
C) 12221
D) 12321
E) 12421
A2. A) 11111 A five-digit palindromic number is precisely determined by the first three digits: the last digit is then equal to the first digit, and the fourth digit is equal to the second digit. The first twelve 5-digit palindromic numbers are thus:

10001, 10101, 10201,.., 10901, 11011, 11111.