How To Reduce PDF Files Sizes And Create A Single PDF File In Linux

I had a nice problem to solve the other day:

I needed to scan some documents in PDF format in Linux.
Once the documents were scanned, though, the file sizes were huge (around 2 or 3 MB per page) and I had no way of scanning more than one page at a time.
I had to send the documents as one PDF and, since it would be an attachment sent via E-Mail, I had to reduce the size of the documents. The original size for the document was around 25 MB, with 10 pages.
The solution I found:
Open the PDF file in Okular, then print the document as a PDF (yes, this may seem weird, but it worked). Each page was reduced to 10% of its original size (each page was around 200 kb after the size compression).
The second part was to "stitch" all pages together, so that it would be one document, instead of 10 separate documents.
This section was accomplished by the use of http://www.mergepdf.net/, where you simply upload the pieces that you want to "stitch" together and the page creates a single file for you.

I hope this helps you, in case you need to reduce sizes and create a single PDF file out of multiple PDF documents.

Regards,

F. Bobbio C.