Competition Math for Elementary School Volume 3

This book can be used by students in grades 3-5: (1) who seek material more challenging than they typically encounter in their math classroom, and (2) who would like to build a solid problem solving foundation for future math competitions such as AMC 8, Mathcounts, and other math competitions.
Each chapter consists of (1) basic skill and knowledge section with plenty of examples, (2) exercise problems, and (3) detailed solutions to all exercise problems.
Volume 4
http://www.amazon.com/Competition-Math-Elementary-School-4/dp/1470130335