Page 12 - NUMINO Challenge_B2
P. 12
Basic Concepts Palindromes
A palindrome is a word or phrase that reads the same forward or backward.
A palindromic number is a symmetrical number, such as 1234321, which
reads the same forward or backward.
Example Numbers that remain the same when their digits are reversed,
such as 1881, are called palindromic numbers. Out of all 4-digit
numbers, how many are palindromic numbers?
Class Notes
Since the last two digits of a 4-digit palindromic number are the first two digits
reversed, the number can be written as
Since the first digit cannot be , digits can be placed in and digits can
be placed in . 4-digit palindromic numbers.
Therefore, there are
Try It Again How many 5-digit palindromic numbers are there?
9Number and Operations
A palindrome is a word or phrase that reads the same forward or backward.
A palindromic number is a symmetrical number, such as 1234321, which
reads the same forward or backward.
Example Numbers that remain the same when their digits are reversed,
such as 1881, are called palindromic numbers. Out of all 4-digit
numbers, how many are palindromic numbers?
Class Notes
Since the last two digits of a 4-digit palindromic number are the first two digits
reversed, the number can be written as
Since the first digit cannot be , digits can be placed in and digits can
be placed in . 4-digit palindromic numbers.
Therefore, there are
Try It Again How many 5-digit palindromic numbers are there?
9Number and Operations
