I need some help€¦

In Excel 2003, I am entering in a column of cells; different numbers that I
want formatted a specific way.

For example:

I enter this number: 31002770004304330

I want to format them like this: 3100-27-7000-430-4330

After I entered the first series of numbers without the dashes, I went to
format cells, selected custom, and enter in 0000-00-0000-000-0000 and applied
this format.

What happen is Excel changes by last 4 numbers in the string from 4330 to
4300 when I enter the data. Why?

I am using the numeric key pad enter a couple hundred of these and dont
want to have to take time to type in each €œ-€œ for the series of numbers.

What am I missing???


Thanks for any help you can give me.