How to Number Rows in an InDesign Table
InDesign tables are often used for product lists, for good reason: The table tools are powerful and the basics are pretty easy to master. But the supplied input (e.g. an Excel file) doesn't always include an extra column with some kind of a numbering system for the items. Of course, that won't stop your client from asking for one! So it's up to us to use InDesign and create just that: an extra column with a numbering system for all the product rows.
The basic setup
Start by creating a table, or placing your input. Remember that we need an extra column (in my case to the far left) that will hold our numbering system. Don't resize the column width to the desired amount just yet because we need to tweak the number options first and that will require some room to work with.
Inserting the number system
There are only a few options in InDesign that can create an automatic numbering system; I'll be using the Bullets and Numbering function. First, place your cursor in the first cell and click the Numbered List button at the top of the screen, located inside of your Paragraph options.
You'll notice that nothing probably happened when you clicked the button; that is because there is no text inside of the cell to number. So InDesign is now waiting for you to type a character, any character. The problem here is that we would like to have a character that takes up no or almost no room. There are a few special characters that take up no room when typed ("zero-width characters"), so I like to use one of those. I usually use the End Nested Style Here, but you can really use whatever you feel like. You can find this character here: Type > Insert Special Character > Other > End Nested Style Here. Now you'll see that InDesign types this character and also starts the numbered list at 1.
Configuring your numbered list
We still need to change a few options. So while the text cursor is still in your cell, let's take a look at the Numbered List options. The quickest way of doing this is by holding down Option/Alt and clicking the same Numbered List icon in the Control panel. In the Numbered List options you can change the notation of the numbered list in the "Number" field. The ^# represents the actual number. By default, you usually see that followed by a period (dot) and ^t (which means a tab character). Delete the ^t at the end; you'll see this change applied to your text if you activate the Preview checkbox. I also want the number to automatically progress so change the Mode from Start At 1 to Continue from Previous Number. When you're done, click OK to close the dialog box. If you want, you can center the number in the cell by using the regular paragraph text options. When you're happy with the way your number looks it's safe to change the size of the cell to whatever width you want.
Applying the number to other cells
You have the number in one cell, but what about the others in the column? Select the entire cell -- be careful: don't just select the text, you need to select the entire cell! The quickest way of doing is is by placing your text cursor inside the cell and then pressing the ESC key on your keyboard. The Esc key toggles between selecting the text and the cell -- you want the cell. Next, copy this cell by using CMD+C (CTRL+C on a PC). Next, select all the other cells in the column -- the cells that you want to have numbering. You can click and drag over the cells with the Type tool to select them all. And finally, paste (Command-V or Ctrl-V). You'll see that all the cells receive a number and the numbers continue the list.
This copy-paste trick works because when you copy a cell, select more than one cell, and paste, the content of the one cell is duplicated into all the other cells!
If you are using this technique on two columns in the same table you'll see that InDesign will change the system and continue counting to the cells on the right. That is because InDesign will scan the table from left to right and then from top to bottom and apply the numbering this way. This can be pretty handy, but this can also mess up whatever you had set up before, so be careful.
If you do want to have two or more consecutive numbered lists across your table it is possible to resolve this by using the List function inside of your Numbered List options. To do this you need to open up your Numbered List options and choose "New List..." from the dropdown menu. There you can rename your new list and save it. Remember you can use as many lists as you want, using 1 per numbered series. This way every number will be faithful to their respective list inside the table.
An alternative way of creating a numbered list is using this free script from Marijan Tompa called TomaxxiFillTable. This script allows you to fill your table with placeholder text, placeholder numbers or a numbered list. Of course this is all placed as typed text so there is no real link between the numbers; in other words, if you remove a row, the numbers won't update. (They will if you use this automatic numbered list trick.)