a palindrome is a number that reads the same forward and backward , such as 787 . how many even , 8 - digit numbers are palindromes ?
"first recognize you only need to consider the first four digits ( because the second four are just the first four flipped ) there are 9000 possibilities for the first four digits of a 8 digit number , 1000 - 9999 inclusive . everything starting with a 2,4 , 6,8 will be odd , which is 4 / 9 ths of the combinations . 4 / 9 * 9000 = 4000 answer : e"
divide(power(const_10, divide(8, const_2)), const_2)