methods and fields are added

A vampire number has an even number of digits and is formed by
multiplying a pair of numbers containing half the number of digits of
the result. The digits are taken from the original number in any order.
Pairs of trailing zeroes are not allowed. Examples include:
1260 = 21 * 60
1827 = 21 * 87
2187 = 27 * 81
Write a program that finds all the 4-digit vampire numbers.