Question

How many positive palindromic integers are 5 digits long 5-digit long and contain 7 or 8?

Answer 1

If the integers only contain digits 7 or 8 we have to consider 3-digit integers:
777
778
787
877
788
878
887
888
The palindromes would then be:
77777
77877
78787
87778
78887
87878
88788
88888
So there are 8 palindromic integers.