Apparently , the 9 digits are pure "text" and not real numeric.
If you notice a small green rectangle at the corner of the cells -
Select the range click on the small icon with the exclamation mark and
choose "convert to number".
Now, you will be able to format the cells as per zip codes.
Micky


"Attman68" wrote:

Hi,

I have a column of data which contains 9 digit numbers. These are zip codes
+ 4. Problem is that we received the data as a continuous 9 digit number
with no hyphen. For some other software we use, I really need the hyphen.
I went to "Format Cell" and found zip+4 formatting and custom formating which
shows "00000-0000." I tried to apply each and nothing happened. I even
created another column, formatted with that cell format and then pasted the
numbers in. Nothing. In other columns, I was able to reformat cell
properties such as turning currency numbers into regular numbers.

Little help? Thanks!