The PDF files that provide either solutions to Puzzlers or further detailed theory and mathematical derivations are opened by the following passwords.
So that I can talk about puzzlers and the like during my demonstrations, the PDF files giving solutions are password protected. After I talk about a given topic or puzzler, I change the PDF file to one having a ..._pw04.pdf extension. These PDFs all have the same password, the pw04 password. This password is "isaac1newton", without the quotation marks. When you download a PDF file you will be asked for this password in order to view the PDF file.