A palindrome number is a number that remains the same when its digits are reversed. For example, 16461 is a palindrome number because it reads the same backward as forward. Palindromic numbers have reflectional symmetry across a vertical axis. The first few palindromic numbers in decimal are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, and so on. Palindromic numbers are most often considered in the decimal system, but the concept of palindromicity can be applied to the natural numbers in any numeral system. Palindromic numbers receive most attention in the realm of recreational mathematics, where a typical problem asks for numbers that possess a certain property and are palindromic.