In The Old Man and the Sea, Santiago has a superstitious attitude to life in general and to numbers in particular. He tells his young friend Manolin that "eighty-five is a lucky number," and he therefore believes that, though he has caught no fish for eighty-four days, the eighty-fifth will be different. The boy suggests using the number eighty-five to make money on the lottery, but Santiago does not have the initial capital to do this.

Santiago's superstitions surrounding numbers seem to be entirely arbitrary and based on wishful thinking. Manolin points out that Santiago once went for eighty-seven days without catching a fish, after which fish were miraculously plentiful for weeks. Santiago, however, dismisses this precedent with the comment that such a thing could not happen again, but he does not justify his view or give any reason why eighty-eight should not be considered his lucky number instead of eighty-five.

Hemingway is typically laconic in his presentation of Santiago's superstitions and does not tell the reader what to think about them. Throughout the book, there is a thin line between superstition and faith, as there is between luck and fate. Santiago is always close to this line, and it is arguably the old man's faith and fatalism that give him his dignity.