When you use several equations in your disquisition, you might want to number the equations within the text. However, if you number one equation in the text, then you must number all of the equations that appear in the disquisition.
You can number the equations sequentially according to the chapter in which they appear (such as 1.1, 1.2, 1.3, 2.1, 2.2, 2.3, and so on), or you can number them in order of appearance, regardless of chapter or section (such as 1, 2, 3, 4, and so on). However, you cannot have two equations labeled as “Equation 1”, for example.
To number an equation, include the equation number in parentheses and place it to the right of the equation. For an example of how to insert an equation into the text, and how to number equations, download this example document of non-text items.
For additional information about how to format equations, see Tables, Figures, Schemes, Etc.
If you use a large number of equations in your disquisition, you might want to include a List of Equations in the prefatory material. For information about how to format lists, see List of Tables, Figures, Schemes, Etc.