Adding to Data

I have about 9000 cells that contain numbers. I need to add some text at the end.

For example, now cells are like this:

10001
10002
10045....

I need to add the following (.gif at the end of each number)
so cells will now look like this:
10001.gif
10002.gif
10045.gif

Anyone know of a way to do this in Excel?

If your data is in col A, in cell B input following formula:
=a1&".gif"
Extend down as necessary by double clicking the handle at lower right corner of the selection border of cell B1

HTH