Each document in your book can be numbered, and these numbers can be used as automatic chapter numbers. Automatic will increment from the previous document’s number, or you can choose “Same as Previous in Book” if it’s still the same chapter but broken into two or more parts, or you can arbitrarily number it anything you want to. This can save time if you have a large number of chapters that change order frequently, since the numbers will update automatically.
We'll work with the existing heading styles. When applying this technique to your own documents, you can modify the heading styles to reflect the properties you need—you're not stuck with the default settings. If, however, the built-in heading styles are already in use because you're working with an existing document, you'll have to create new styles. Avoid this route when possible. We'll be changing properties for the numbering scheme and not the actual heading styles.
The easiest way to implement a numbering scheme for headings is to add one to a heading style. To illustrate, we'll modify Heading 1 by adding a numbering scheme. First, right-click Heading 1 in the Styles gallery (in the Styles group on the Home tab). Then, choose Modify as shown in Figure A to launch the Modify Style dialog. If you thumb through the default properties, you'll not find a numbering scheme (Figure B). Click the Format button and choose Numbering as shown in Figure B. If necessary, click the Numbering tab. Choose the predefined scheme that's the best match for what you want (Figure C). document numbering in word