"Numbers" redirects here. For the episode, see Numbers (episode). The numbers 4, 8, 15, 16, 23 and 42 frequently recurred in Lost. Each corresponded with one of the final candidates to replace Jacob as protector of the Island. The numbers also formed the coefficients in an equation that predicted mankind's extinction. Jacob and his brother, the Man in Black, lived on the Island for over two thousand years. During this time, the two engaged in a rivalry over the nature of humanity. Jacob brought