when does 2 plus 2 not equal 4
2 + 2 = 5 The equation 2 + 2 = 4 has been proverbial as the type of an obvious truth since the 16th century, and it appears as such in Johann Wigand's 1562 De Neutralibus et Mediis Libellus: "That twice two are four, a man may not lawfully make a doubt of it, because that manner of knowledge is grauen [graven] into mannes [man's] nature."[2]