If a sequel has a number in the title, that number is usually 2, indicating that the work is the second in the series (followed by 3, etc.). However, sometimes the original work already has a number greater than one in the title. In that case, the sequel title will often add one to that number, instead (with a possible in-story justification).
The original work will often have a better justification for using a number in the title than the sequel does. So, the title of the film The Whole Nine Yards refers to a common English expression, but The Whole Ten Yards doesn't.
- 21 Jump Street and 22 Jump Street
- Lampshaded fantastically in the end credits, showing the events of 23 Jump Street. And 24 Jump Street... And 25 Jump Street...
- Ocean's Eleven, Oceans Twelve, and Oceans Thirteen
- The Three Musketeers (1973) and The Four Musketeers
- The Whole Nine Yards and The Whole Ten Yards
- 101 Dalmatians (the 1996 live action version) and 102 Dalmatians (its 2000 sequel).
- Three-Headed Shark Attack is the sequel to Two-Headed Shark Attack, not the third in a series. Confusingly, 5-Headed Shark Attack is the next one in the series, with Six-Headed Shark Attack after that, skipping over a hypothetical Four-Headed Shark Attack.
- The announced title for a planned sequel to Twins (1988) was Triplets. It's been in Development Hell for a long time and with Ivan Reitman's passing the chances of it getting made got slimmer.
- The Magic by the Numbers trilogy by Lyndon Hardy: Master of the Five Magics, Secret of the Sixth Magic, and Riddle of the Seven Realms.
- Metro 2033, Metro 2034, and Metro 2035 by Dmitry Glukhovsky.
- Inverted by Matthew Reilly's Jack West thrillers, which begin with Seven Ancient Wonders and count down to The One Impossible Labyrinth.
- Soul-Junk uses and inverts this. Their first album was named 1950. Albums that followed counted up (1951, 1952...), while EP's counted down (1949, then 1948...).
- 1942 and 1943: The Battle of Midway. 1941: Counter Attack was actually the third game (fourth if you count 1943 Kai).
- While not a sequel, the hard mode in killer7 retitles the game killer8 due to the addition of a young Harman Smith as a persona.
- Inverted by the fan game Super Mario 63 which subtracts 1 from Super Mario 64 rather than adding.