I have these asset ID's in a CMS and I need to update them all with regular expresssions.

They are 8 or 9 characters in length and made of all numeric characters (0-9). Is there a way to match only 8 or 9 numbers? I'm afraid I may not be using the right keywords in my google search to figure this out and I haven't found anything in my cheat sheets or books yet so I'm hoping someone here might be able to point me in the right direction.

seth