# How to write the equation number manually? [duplicate]

Does anyone know how to number an equation manually? I know using automatically numbers the equation but I want to number it manually.

Like this:

ax=b                      2.1

ax=b                      2.2


etc.

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Any specific reason, why you want to number them manually? – samcarter Feb 25 at 17:20

You can use the amsmath package and the \tag command. If you don't want the parenthesis, use \tag*.
\documentclass{article}
$$ax= b \tag{2.1}$$

And still be able to use \label and \eqref! – egreg Feb 24 at 18:13