## Lesson: Adding and Subtracting Decimals

Introducing the Concept

Adding and subtracting decimal numbers follow the same rules as adding and subtracting whole numbers. The trick is to be sure that the place values line up. Because students are used to lining up numbers starting on the right, this is easy for numbers with the same number of decimal places, but errors start to occur when they do not.

**Materials:** grid paper or notebook paper turned sideways, play coins and bills

**Prerequisite Skills and Concepts:** Students must be comfortable adding and subtracting whole numbers with and without regrouping.