A word that reads the same from left to right and right to left is a palindrome. For example, "I", "noon" and "racecar" are palindromes. In this question, we consider palindromic integers such as 101 and 66. Note that the first digit of an integer cannot be 0. How many positive 5-digit integer palindromes

• are there?

• are even , for example 29192?

• contain 7 or 8, for example 27172 or 38783?