If I book is missing the dust jacket where do you find the ISBN#?

Try the copyright page

If it's not on the copyright page, check the publication date - if it's older than 1970, it won't have an ISBN.

Thanks, I was just trying to put it on my TBR - I don't see it anywhere, no big deal, I will pull it up by title - I doubt I will trade it since the cover is missing.

You should look at the copyright page.  Please don't post it just by title - this can lead to a "Received With A Problem".

As for the dust jacket, you can definitely post hardbacks without them.

There is nothing on the copyright page, just an eight digit number that doesn't pull anything up.  It is not old, 2007.  But you are right, I looked in some other books and saw that thye do have the ISB# on the copyright page.

Anywho - I read it and plan to keep it, so I won't be posting it.  Thanks for all the help everyone.

If it's not on the copyright page, it might be a book club edition, which don't have ISBN's.

Some older book club editions don't have ISBNs.  Almost all of the ones issued in the past few years have an ISBN and it's often the same as any other hardcover edition.