How many 5-digit palindromes contain only even digits?

The correct answer is - 900

Step-by-step explanation:

A palindrome is a positive integer that is same whether read from left to right or from right to left. For example, 123321 palindromes.

An n-digit palindrome is determined from the first  n/2  digits if n is even, and from the first n+1/2 digits if n is odd.

Therefore, if  n  is even, there are  9×10⁽n⁻²/²⁾  palindromes; and if n is odd, there are  9×10⁽n₋²/²⁾ palindromes.  where n is number of digits.

For  n=5 , there are  9×10²=900 palindromes