Understanding Number & Operations is for parents, teachers & tutors who believe that school mathematics should encompass more than vocabulary, notation, and computational skills. It must also foster curiosity, encourage persistence, structure discourse, and facilitate discovery, problem-solving, critical thinking, and proof. For that to happen, mathematics education must be about more than "how"; it must also be about "why". This book was written for adults who want to help students make the most empowering discovery of all, that they are capable of authentic mathematical inquiry, discovery, and reasoning. Understanding Number & Operations is not a step-by-step "how to" guide for parents of students in different grades. It is food for thought for adults seeking deeper insights into the foundations of arithmetic and number theory.