This is the second book of the Math Contest Books Series -- This book introduces the new methods to solve balls and boxes distribution problems. The book can be used by students preparing for math competitions such as Mathcounts, and AMC 8/10/12.
Each chapter consists of (1) basic skill and knowledge section with examples, (2) exercise problems, and (3) detailed solutions to all problems.
First book of Math Contest Books Series. The Mass Points Method:
https: //www.amazon.com/Mass-Points-Method-Yongcheng-Chen/dp/1523265884
Third book of Math Contest Books Series: The Area Method
https: //www.amazon.com/dp/1540856410