These are notes on elementary number theory; that is, the part of number theory which does not involves methods from abstract algebra or complex variables.
The first link in each item is to a Web page; the second is to a PDF file. Use the PDF if you want to print it. There are videos for some of the sections, but they don't cover everything in the printed notes.
These notes have been revised at various times (2008, 2011, 2016).
Bruce Ikenaga's Home Page