1. How many 5-digit numbers are palindromes?
2. How many 6-digit numbers are palindromes?
3. How many 4-letter words (including nonsense words) are palindromes?
4. How many 3-letter words (including nonsense words) are palindromes?
A number or word is said to be a palindrome if it reads the same backward as forward (e.g., 58485 or radar).