#1**+1 **

900 since the first three numbers are the only ones that matter there are 9*10*10 options

Guest Apr 22, 2019

#2**-3 **

If you start to construct a five digit palindrome then the first digit can be any digit from 1 to 9. That is, there are nine choices for the first digit, which must then also be the fifth digit.

For the second digit you can choose any digit from 0 to 9 so there are ten choices for the second digit. This digit must also be placed in the fourth position if the number is to be a palindrome.

By the same reasoning there are ten choices for the third digit and this completes the number. Thus there are 9 x 10 x 10 = 900 choices for the first three digits and hence 900 five digit palindromes greater than or equal to 10,000.

Source and credits:

http://mathcentral.uregina.ca/QQ/database/QQ.09.00/jacky2.html

~~Hypotenuisance

Hypotenuisance Apr 22, 2019