So you're claiming Number 5 never existed, Though the next game is Number 6?
It's painfully obvious that this game is actually Call of Duty 5, They just did not feel the need to add a number.
All the "Little" CoD games were console exclusive, and therefore, do not count to the main 5 games.
CoD5: World at War
CoD6: Modern Warfare 2
Or just Modern Warfare 2, The idea is the same, as well as the fact that these games are still part of the main series.
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