Add calcuation field in sale invoice

How to add numeric column for each line of item in sale invoice effecting total amount?

There is a Guide telling how to do that.

Can you please share the link with exact page number if possible?

I want to effect both amounts: total amount of each line of items and invoice total.

You can search the Guides. But what I was referring to was adding line item numbers.

Search the forum for previous discussions about totaling quantities.