In this activity, we will add three decimal numbers, making sure that the decimal points are in a vertical line before carrying out an addition in columns.

Example

Add 157.2 + 198.4 + 6

Answer

First, we need to make sure that all three numbers have the same number of decimal places so that we can line the decimal points up easily.

157.2 and 198.4 are fine because they both have one digit after the decimal point so we can line them up easily.

6 is a bit of a problem though! We have to convert 6 to 6.0 before we can add it to the calculation.

So 157.2 + 198.4 + 6 = 361.6

Do you see how easy it is once we have given them all the same number of decimal places, and lined up the decimal points?

Let's have a go at some questions then!