# Using doubling or halving to calculate efficiently

In this lesson, we will use doubling and halving skills to efficiently calculate multiplication and division involving a factor of 2.

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
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.What is the commutative law in multiplication?

1/5

Q2.What is the associative law in multiplication?

2/5

Q3.Which law do you use when multiplying 2 x 5 x 6?

3/5

Q4.When multiplying 6 x 2 x 5, which is the most efficient order?

4/5

Q5.8 x 4 x 10 = 4 x 10 x 8. True or false?

5/5

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
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.What is the commutative law in multiplication?

1/5

Q2.What is the associative law in multiplication?

2/5

Q3.Which law do you use when multiplying 2 x 5 x 6?

3/5

Q4.When multiplying 6 x 2 x 5, which is the most efficient order?

4/5

Q5.8 x 4 x 10 = 4 x 10 x 8. True or false?

5/5

# 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:

• Click "Close Video"
• Click "Next" to view the activity

Your video will re-appear on the next page, and will stay paused in the right place.

# 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.

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
Quiz:

# Using Doubling or Halving to Calculate Efficiently Quiz

Can you double and halve to calculate efficiently? Take the quiz to test out your new learning.

Q1.To multiply by 4, you can double and double again.

1/5

Q2.To divide by 4, you can halve then halve again.

2/5

Q3.What is 72 divided by 4?

3/5

Q4.What is 17 x 4?

4/5

Q5.To multiply by 8 you can multiply by 2, 3 times. This is the same as multiplying by 6.

5/5

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
Quiz:

# Using Doubling or Halving to Calculate Efficiently Quiz

Can you double and halve to calculate efficiently? Take the quiz to test out your new learning.

Q1.To multiply by 4, you can double and double again.

1/5

Q2.To divide by 4, you can halve then halve again.

2/5

Q3.What is 72 divided by 4?

3/5

Q4.What is 17 x 4?

4/5

Q5.To multiply by 8 you can multiply by 2, 3 times. This is the same as multiplying by 6.

5/5

# Lesson summary: Using doubling or halving to calculate efficiently

## Time to move!

Did you know that exercise helps your concentration and ability to learn?

For 5 mins...

Move around:
Climb stairs

On the spot:
Chair yoga