Four is the magic number in Michael Martone's "Four for a Quarter." In subject--four fifth Beatles, four tie knots, four retellings of the first Xerox, even the sex lives of the Fantastic Four--and in structure--the book is separated into four sections, with each section further divided into four chapterettes--"Four for a Quarter" returns again and again to its originating number, making chaos comprehensible and mystery out of the most ordinary.