Captain Ramshackle wants to know which number, when multiplied by itself, will give the answer minus one

Captain Ramshackle wants to know which number, when multiplied by itself, will give the answer minus one. And that question doesn't have an answer!« »But that doesn't seem such a difficult question,« said Alice. »Well, as you must surely know,« the termite replied, »one times one is one, and minus one times minus one is also one, because two negatives always make a plus.« »Do they?« »They do indeed.« »But I was taught that two wrongs do not make a right.

Джефф Нун, Автоматическая Алиса