Kumon Math Skills Workbooks are unique because they focus on teaching one specific skill from start to finish. With just the right amount of practice, children master each topic and gain confidence without becoming bored or frustrated. This workbook will improve and expand on the skills acquired in My Book of Simple Subtraction. In this book, children will first practice how to subtract the numbers 1 through 9, and then they will build on this skill by learning how to subtract numbers 1 through 20. The purpose of this book is to prepare children for higher-level mathematics by improving their basic subtraction skills.