Find the total number of four-digit palindromes. (Recall that a palindrome is a nonnegative sequence of digits which reads the same forwards and backwards, such as 1331. Zero cannot be the first digit.)

gueesstt
May 13, 2018

edited by
Guest
May 13, 2018

#1**+2 **

There are two methods to do this problem.

Method 1: Pattern Finding

There are 9 palindromes with 2 digits

There are 90 palindromes with 3 digits

There are 90 palindromes with 4 digits

Method 2: Counting

The 4 digit palindrome is in this format:

ABBA

There are 9 choices for A

10 for B

9*10=90

I hope this helped,

Gavin

GYanggg
May 13, 2018