MATH TEXTBOOK (WITH INTERACTIVE FEATURES)
Link:
http://www.mathopenref.com/index.html
What can a student do after they have returned the textbook to their school?
Simple. Checkout the information at Math Open Reference.
Although this site does can some annoying side ads, the content seem reasonable from what I have read.
I would recommend this site as a source of math information. Perhaps it can help you learn.
http://www.mathopenref.com/index.html