3.2 Introduction and Key Insights

With practice, adding and subtracting negative numbers feels just like adding and subtracting positive ones. For example, you can add $-5$ and $-3$ in several ways. We can write it out as $-5+(-3)=-8$. You can think of negative quantities as "debts" or money owed. Combine a debt of $5 with a second debt of $3, and you obtain a total debt of $8. We can use other models to interpret and add negative numbers, such as a number line model.