
A textbook on mental math skills for American schoolchildren, covering addition, subtraction, multiplication, and division. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This...

A textbook on mental math skills for American schoolchildren, covering addition, subtraction, multiplication, and division. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This...