Y by
Let
be a positive integer. A positive integer
is called a
-good number if it satisfies
the following two conditions:
1.
has exactly
digits in decimal representation (it cannot have leading zeros).
2. If the first
digits and the last
digits of
are considered as two separate
-digit
numbers (which may have leading zeros), the square of their sum is equal to
.
For example,
is a
-good number because
Find all
-good numbers.



the following two conditions:
1.


2. If the first




numbers (which may have leading zeros), the square of their sum is equal to

For example,


![\[(20 + 25)^2 = 2025.\]](http://latex.artofproblemsolving.com/5/c/5/5c51bca485cea6c3750c48c09091eb5fd72b5192.png)

This post has been edited 3 times. Last edited by CSJL, Mar 6, 2025, 8:27 AM
Reason: Format
Reason: Format