Kaprekar number

A Kaprekar number is a special kind of number in recreational number theory. A non-negative integer \( n \) is called a Kaprekar number if the following condition holds: 1. Square the number \( n \) (calculating \( n^2 \)). 2. Split the resulting square into two parts: the right part containing \( d \) digits (where \( d \) is the number of digits in \( n \)), and the left part containing the remaining digits.