Problem Statement
9 is a Kaprekar number since
9 ^ 2 = 81 and 8 + 1 = 9
297 is also Kaprekar number since
297 ^ 2 = 88209 and 88 + 209 = 297.
In short, for a Kaprekar number k with n-digits, if you square it and add the right n digits to the left n or n-1 digits,
the resultant sum is k.
Find if a given number is a Kaprekar number.