Hi,
Do you require the Zipcode to be saved as a number rather text?
You can format your cell(s) by doing this.....
Highlight your cell(s)
Right Click
Click Format Cells
Click Custom
In the white box underneath Type put this....
0000"-"0000
Click Ok.
You can now type your number in like this....
156665021 and Excel will format it to 15666-5021.
I hope that works for you.
Good luck.
Ak