Alex a bit confused on the question best bet is to reference you to Access Beginner

Give that a shot and see if it helps.

When you say "The Number", are you referring to the autonumbers? If so, see this AutoNumbers Are NOT For You

If you are referring to a regular numbered field, use Update Queries

Also watch Automatic Record Numbering

If you are not speaking about the AutoNumber but need to still  order your records check out the Custom Sort Order and the Automatic Record Numbering videos.
Those will both show you how to order the records in a specific manner.

You might want to consider the TechHelp membership as well.  The extended cuts for those links cover much more than the free videos.   See:  TechHelp Memberships

Hi Alex, we typically don't do this because even if you don't add or delete records, a table can be sorted, filtered, queried, etc. which will also render your numbering useless.  You can create such numbering for display purposes (with VBA, for instance).  But we typically don't put such numbers inside a table itself, due to precisely the reason you're facing -- you have to redo the numbering every time the table is changed.

Legacy Tip: Row Number in a Query

Thank you for all the replays. I not talk about AutoNumbers.
Let me tried explain better: in a production factory are the "steps", "phases" how products are made. So on the table I will write down this steps ("the production table"):
- phase 1: lay down the material;
- phase 2: upload the drawing i the cutting machine;
- phase 3: turn on the vacuum;
- phase 4: cut the material;
.......................................................
- phase 200: put the label on the box.

I finish the tables with 200 records, phases/steps, but I forgot something: - phase 4: put the protection on
I goo in the table and insert this new phases/steps. Now I have 2 phase/steps number 4.
What I need:
- when I introduce a new number 4 phase/steps the old number 4 transform in phase/steps number 5, 5 in 6, ..... 200 in 201

Make a copy of your Table (Structure only) and use a couple of Append Queries to add the missing record.

1. Run the first Append Query.
2. Add the missing record to the  temporary Table.
3. Run the second Append Query.

The screenshot below shows how I accomplished this.

I know what you need check this one out.  Automatic Record Numbering and its a tech help video.

V/r
Juan