Gray is apprehensive about her first day at her new school, until she meets Pi, a tiny math guru who assures her that she will meet and befriend other mathematically precocious students like herself. Mrs. Googol-Plex's classroom is a magical place where Gray, Alex, and friends learn simple and surprising new ways to understand subtraction. Gone is the old method of crossing out smaller digits above larger digits, which confuses the issue of place value. Instead, children will learn alongside Gray, Alex, and their friends that there are several ways to do subtraction that allow them to use fundamental mathematical concepts logically—and to have fun in the process. This book includes both the novel and an instructor section, in which the authors explain how to take the mystery out of subtraction.