diff --git a/source/chapter2/20_Type_Casting.md b/source/chapter2/19_Type_Casting.md similarity index 100% rename from source/chapter2/20_Type_Casting.md rename to source/chapter2/19_Type_Casting.md diff --git a/source/chapter2/19_Nested_Types.md b/source/chapter2/20_Nested_Types.md similarity index 100% rename from source/chapter2/19_Nested_Types.md rename to source/chapter2/20_Nested_Types.md