I'd never write, "I'm all at six's and seven's."

You would instead write, "I'm all at sixs and sevens."? The sevens looks ok to me, but not sixs or do we add es and make it sixes? Now I don't know which looks right anymore! [very confused-e]

EDIT: Our wonderful "Spell Check" feature here says its "sixes and sevens". But do we believe ænigma?