Hodgetts derivative is a unique, highly illogical, branch of mathematics, invented by one Jonathon Hodgetts who dwells in Norfolk. It is speculated that inbreeding has resulted in his unusual powers of mathematics. Hodgetts derivative can be applied to almost any formula, inequality or person suffering from non-existant personality disorder. It is also speculated Jonathon Hodgetts suffers from the aformentioned disorder (non-existant personality disorder).