7. Decimal operations

Lesson

In previous lessons, we have looked at how to add and subtract decimals with up to 2 decimal places. We'll apply the same strategies when adding bigger decimals, so let's start with a bit of review

Find 13.74+37.26 giving your answer as a decimal.

Worked Solution

Find 53.29-42.29, giving your answer as a decimal.

Worked Solution

Idea summary

When we add and subtract numbers with decimals, the process is exactly the same as when we work with whole numbers. We always start from the far right place value position, and move left, regrouping if we need to.

In this video, we work through an example of adding two numbers with 3 decimal places.

In this video, we use an example of adding two numbers with 3 decimal places where we need to rename some decimals, after regrouping.

Find 563.362 + 331.495, writing your answer in decimal form.

Worked Solution

Idea summary

We can use a vertical algorithm to add decimals up to thousandths.

This video works through subtracting large numbers with decimals in the thousandths.

Find 96.689 - 83.413, writing your answer in decimal form.

Worked Solution

Idea summary

We can use a vertical algorithm to subtract decimals up to thousandths.

Add and subtract decimals, with and without digital technologies, and use estimation and rounding to check the reasonableness of answers