Numbering equations
Equation numbering is one of OOoMathâ€™s best hidden features. The steps are simple, but obscure:

Start a new line.

Type â€œfnâ€ and then press F3.
The â€œfnâ€ is replaced by a numbered formula:

(2)

Now you can doubleclick on the formula to edit it. For example, here is the Riemann Zeta function:

(3)

You can reference an equation (â€œas shown in Equation (2)â€) with these steps:

Insert > Crossreference..

Click on the References tab (Figure 403).

Under Type, select Text.

Under Selection, pick the equation number.

Under Format, choose Reference.

Click Insert.
Done! If you later add more equations to the paper before the referenced equation, all the equations will automatically renumber and the crossreferences will update.
TIP

To insert the equation number without parenthesis around it, choose Numbering under Format instead of Reference.
