Modern adult life revolves around monumental purchases such as a house, a car, and a deluge of other items that almost universally require entering a formal interest bearing debt obligation. As such, understanding the governing mathematical equations that dictate these interest bearing debts is critical to a practical education. This book intends to provide a basic mathematical understanding of the underlying rules of interest bearing debt taking no prior understanding of mathematics for granted. This book is tailored to take the student all the way from addition to continuous compounding interest in the least painful and most efficient path possible. The mathematics of interest is not a hard subject and I prove this through an easy to read and obvious approach. I have written this book with the following type of reader in mind; The fresh on their own young adult entering a world of credit cards and student loans, The new home buyer bewildered by the fast and seemingly secret world of interest bearing loans, The debtor well above their head in obligations who would like to know why they never seem to pay off their debt by paying the minimum payment. It is my sincerest hope that this book helps you with your needs.