Palindromes

Happy ''Teacher's Day'' to all the teacher's viewing my blog. Palindromes are words or numbers that are same when read from front or back like madam, mom,  pop, they can be numbers also like 1331 121 999etc. Today I will share some problems with you involving Palindromes.
Problem no. 1: Find the total no. of 4-digit Palindromes?
Problem no. 2: Find the total no. of 5-digit Palindromes?
Problem no. 3: How many 7-digit Palindromes are there that do not start nor end with 1.
  Solution for 1: A four digit Palindrome is like ---- where the first and the last digit is the same and the second and the third digit are the same. So for the first and the last digit we have 9 choices(0-9) and for the second and the third we have 10 choices (0-10). Answer 9 multiplied by 10.
Solution for 2: A five digit Palindrome is like ----- where the first and the last digit are same and the second, third, and the fourth digit are the same.So for the first and last digit we have 9 choices(0-9) , for the 2nd, 3rd and 4th we have 10 choices(0-10) each. Answer-9 multiplied by10 multiplied by 10.
Solution for 3: a seven digit Palindrome is like ------- for the first digit we have 8 choices because it cannot be 0 or 1, for the 2nd, 3rd, 4th,5th,6th we have 10 choices each (0-10), and for the last digit we have 9 choices  since it cannot be 1. Answer is 8 multiplied by 9 multiplied by 10 multiplied by 10 multiplied by 10 multiplied by 10 multiplied by 10. I came across this problem when I was reading a book by Mr ''Titu Andreescu'' . Bye-Bye.