Procedure for Background Numbering (classic)

Press [Edit / Color].

Operation panel screen illustration

Press [Stamp] twice.

Press [Background Numbering].

Enter the number to start counting from with the number keys, and then press [].

Operation panel screen illustration

Press [Stamp Color].

Select the stamp color, and then press [OK].

Press [OK] three times.

The numbers appear to overlap the copied image in some cases.
You can change the settings for Background Numbering under [Background Numbering] in User Tools. For details, see Background Numbering.