Buy the entire set of Ed Zaccaro math books and save $50.00. Regular (non-spiral bindings only).
 

Books include: 
Primary Grade Challenge Math 
Challenge Math for the Elementary and Middle School Student 
Real World Algebra 
Becoming a Problem Solving Genius: A Handbook of Math Strategies 
The 10 Things All Future Mathematicians and Scientists Must Know (But are Rarely Taught) 
25 Real Life Math Investigations That Will Astound Teachers and Students
Scammed by Statistics: How We are Lied to, Cheated and Manipulated by Statistics...and Why You Should Care
Upper Elementary Challenge Math

Entire set ships for minimum shipping charge of $4.95.