Apple Numbers '09 - Manual (Page 110)

8 In the topmost format field, define the display format you want to use if a number
doesn’t meet any of the conditions.
You can use the Entered Text element to display predefined text if a text value is
entered instead of a number. See “Creating a Custom Text Format” on page 111 for
more information.
9 In the Name field, type a name for your number format, and then click OK to save it
and apply it to selected cells.
Custom format names are listed in the Cell Formats pop-up menu in the format bar
and in the Cell Format pop-up menu of the Cells inspector.
Creating a Custom Date/Time Format
To define your own display format for date and time values in table cells:
1 Select one or more cells.
2 Do one of the following:
Choose Custom from the Cell Formats pop-up menu in the format bar. Â
Choose Custom from the Cell Format pop-up menu in the Cells inspector. Â
Choose Format > Create Custom Cell Format. Â
3 From the Type pop-up menu, choose Date & Time.
4 Define your date/time format by dragging the (blue) elements from the Date & Time
Elements box into the format field above the box.
110 Chapter 4 Working with Table Cells