The first step to make sure you are adding these correctly is to rewrite the problem so that they are on top of each other. You will need to make sure the decimal points are lined up on top of each other because when you add these, you will add the place values that are the same (when adding anything together your units must be the same). When adding with decimals, the place values will line up if you line up the decimal points.After that, add the numbers furthest to the right because that is your smallest place value.