Layout for a deck of cards

For numbering just the front side, I'd go with using text frames on each front card in InDesign—makes it easy to control, and you can set up auto-numbering so it doesn’t get crazy tedious, especially if it’s a bigger deck.

@mathiasmazzetti as Peter pointed out this could be produced as a work and turn job. An alternative for the numbering could be setting it up directly in InDesign with numbering across stories. Create a text frame and activate numbering, add a space character then edit the list and numbering options as in the screenshots below (that will eliminate the dot after the number). You can use either Paragraph or Character Styles for the numbers. That should work, too.

How many sets are you going to print?

YOu can set this up with the front and back next to each other and print as a work and turn job so you get two identical sets per sheet when you print both sides or you can print fronts on one side and backs on the other. It works out to the same number of plates either way.

A far as numbering, I would make a numbered list in Excel where it's easy to auto-fill a column with progressive numbers, then save as a .text file. Put a text frame in each card that needs a number on your Master/Parent page and thread them together. Create a pargraph style fior the numbers that includes Start in Next Frame and place the text file to number the cards.