Mental Addition and Subtraction

In this lesson, we will use mental calculation strategies to add and subtract decimal numbers.

This quiz includes images that don't have any alt text - please contact your teacher who should be able to help you with an audio description.

Quiz:

Intro quiz - Recap from previous lesson

Before we start this lesson, let’s see what you can remember from this topic. Here’s a quick quiz!

Q1.Which addition expression matches 231.5

1/6

Q2.If 1 is the whole and 0.8 is a part, what is the other part?

2/6

Q3.If 5 is the whole and 2.1 is a part, what is the other part?

3/6

Q4.If 10 is the whole and 7.3 is a part, what is the other part?

4/6

Q5.If 10 is the whole and 1.6 is a part, what is the other part?

5/6

Q6.If 10 is the whole and it is made of 3 parts. What could the parts be?

6/6

This quiz includes images that don't have any alt text - please contact your teacher who should be able to help you with an audio description.

Quiz:

Intro quiz - Recap from previous lesson

Before we start this lesson, let’s see what you can remember from this topic. Here’s a quick quiz!

Q1.Which addition expression matches 231.5

1/6

Q2.If 1 is the whole and 0.8 is a part, what is the other part?

2/6

Q3.If 5 is the whole and 2.1 is a part, what is the other part?

3/6

Q4.If 10 is the whole and 7.3 is a part, what is the other part?

4/6

Q5.If 10 is the whole and 1.6 is a part, what is the other part?

5/6

Q6.If 10 is the whole and it is made of 3 parts. What could the parts be?

6/6

Video

Play video

Click on the play button to start the video. If your teacher asks you to pause the video and look at the worksheet you should:

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Worksheet

These slides will take you through some tasks for the lesson. If you need to re-play the video, click the ‘Resume Video’ icon. If you are asked to add answers to the slides, first download or print out the worksheet. Once you have finished all the tasks, click ‘Next’ below.

This quiz includes images that don't have any alt text - please contact your teacher who should be able to help you with an audio description.

Quiz:

Mental addition and subtraction

Don’t worry if you get a question wrong! Forgetting is an important step in learning. We will recap next lesson.

Q1.Which addition expression matches 653.3

1/6

Q2.What is 4 tenths add 3 tenths?

2/6

Q3.What is 9 tenths subtract 4 tenths?

3/6

Q4.What is 0.8 add 0.6

4/6

Q5.What is 1.6 - 0.7?

5/6

Q6.What is 0.9 add 9 tenths?

6/6

This quiz includes images that don't have any alt text - please contact your teacher who should be able to help you with an audio description.

Quiz:

Mental addition and subtraction

Don’t worry if you get a question wrong! Forgetting is an important step in learning. We will recap next lesson.

Q1.Which addition expression matches 653.3

1/6

Q2.What is 4 tenths add 3 tenths?

2/6

Q3.What is 9 tenths subtract 4 tenths?

3/6

Q4.What is 0.8 add 0.6

4/6

Q5.What is 1.6 - 0.7?

5/6

Q6.What is 0.9 add 9 tenths?

6/6

Lesson summary: Mental Addition and Subtraction

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