In The Old Man and the Sea, the old man believed that the lucky number was 8. In the novel, the old man San Diago finally won a marlin after fighting a shark for 84 hours. However, he did not celebrate for too long because he thought it was just a "lucky number" in his life. In the following journey, he experienced many difficulties and setbacks, but he always persevered and finally got what he wanted. Therefore, the old man believed that the lucky number 8 also represented his indomitable spirit and perseverance.