NWP does not have an option for numbering equations... NWP should place an equation at center and corresponding number on the right side of the page.
I developed a new way, and I did not find the post which describes the same way I do, so I think I should note it here.
My way is the combination of "writing direction right to left" and creating new paragraph style.
1. Create new list style for "numbered equation". Just select "numbered list" then add "(" and ")" before and after number for Level 1.
2. Create new paragraph style, then name "equation numbered" or whatever you like
3. Insert the "numbered equation" list.
4. Choose "writing direction right to left" in Format => Paragraph writing direction.
5. Choose "right" for text alignment
6. Choose "center" for tab stop arrow, which is located on the right side of ruler
7. Locate the tab stop arrow at the center of the page.
That is it for setup.
Before inserting equation, first you have to hit tab key to make one tab space. You will see why this tab space is required. Insert your equation, then select "equation numbered" in paragraph style.
This method works since inserted equations are image.
You might want to add "," and "." after your equation in your equation editor since it is hard at least for me to modify the paragraph with writing direction right to left.