Use the new toolbar that appears below the “Organize Pages” toolbar to specify how your document should be split. Using the “Number of pages” dropdown menu, your document can be split in three ways: by Number of pages, File Size, and Top level boo

Double-click the PDF you want to split. PDFs are symbolized by a square icon showing a small preview of the PDF's first page and the red square Adobe icon symbol.

How to Split PDF Files. PDF documents are often used because they help preserve the original content of the document, but this can make splitting the file up a little more difficult than other document formats.