Introduction to American Elementary Mathematics (a set of ***6 volumes) (Volume 1-4): a complete K- 12 mathematics course, from counting to calculus. -Ray&; #39; The math series starts counting from the level before literacy; Then take the children through addition, subtraction, multiplication, division and other operations until calculus, and teach concepts through detailed explanations and a large number of exercises. Ray&# 39; S series provides a very rich mathematics course.