My parts in a paper are numbered as 1, 2, 3, .... Sub parts are labeled as 1-1, 1-2, 1-3, .... For instance the 2-12 refers to part 2 of the article and sub part is 12. Now I want Word to label Subs automatically. It helped while I type 2-12 wrongly, Word correct it.
Word corrects numbers of Parts, if typist types it wrongly, but I need to expand it to Subsections too.


Is it possible?

See How to create numbered headings or outline numbering in Ribbon Versions of Word by Shauna Kelly

Charles
Thank you very much.
I did it, but still have a problem.
Have a look at my photo:
1.jpg
Red boxes have not be the same. they have to be continuous (e.g. SubPart11 has to be 1-1-1-2 not 1-1-1-1).
What mistake i did?

Our communication is not the best.
Go back and re-read the article.
It is picking up the number 3 from the numbering applied to the heading 1 above.
To change the number, you apply a style. Here you seem to have two chapter 2's for some reason.

Charles
It done. Thank you very much.
I want Word number each chapters or parts AUTOMATICALLY, not manually. I want After pressing Enter, Word does it itself, without changing Style to one of Headings. How this can be done?
It seems the article says nothing about.

You set up the styles with the setting of "Style for following paragraph" set to do this. I.e., in heading 1 style you have it set for the following style to be heading 2 rather than normal. I have my heading 1 set to be followed by heading 2, and my heading 2 set to be followed by heading 3.

This is done in the modify style dialog.

Note also that if you are using the built-in heading styles, there are built-in keyboard shortcuts for Heading 1-Heading 3. Ctrl+Alt+1 = Heading 1
For more shortcuts, see Heading Style Keyboard Shortcuts Add-In for Headings 4-9.

Note, it is not required that you use the built-in heading styles, you can use your own. Using the heading styles is usually easier. The formatting of the styles can be modified to match what you want.

It is essential, in any document which is going to be heavily edited, to have the numbering linked to styles, though.

Going a bit further...
Word cannot read your mind. You need to tell it what to do. If you do, it will do it if it can.

If your have your numbering linked to styles, picking a style is one way to tell it what you want; the keyboard shortcuts can help with that. So is telling a style to use a different style (with a lower numbering level) for the following paragraph.

Unless everything you are writing is numbered, at some point you will want Word to produce an unnumbered paragraph as the next paragraph. I generally tell heading 3 that I want the following paragraph to be the unnumbered, body text style. The same is true for headings 4-9. For me, Word then does what I want most of the time.