Regex Editor & Tester

Matches integers wrapped in square brackets that are divisible by 4 (n mod 4 == 0), with an optional leading + or - sign. It implements the divisibility-by-4 rule: single digits 0, 4, or 8, or numbers whose last two digits have an even tens digit followed by 0/4/8, or an odd tens digit followed by 2/6. Useful for extracting or validating multiples of 4 in text, e.g. '[12]', '[-104]', '[8]'.