# Using derived facts to multiply mentally

In this lesson, we will use our knowledge of multiplying and dividing by 10, 100 and 1000 to derive facts from known facts. We will then use the distributive law and derived facts to multiply by choosing the most efficient and effective representations.

#### 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.The strategy of separating a number into its individual units of value is commonly known as?

1/5

Q2.Half of 24 is also the same as:

2/5

Q3.The bar model below is used to help divide or multiply numbers. What number should be placed in the top white boxes?

3/5

Q4.Which of the following number sentences will help you to solve the calculation 25 x 8?

4/5

Q5.Which derived fact helps me to mentally solve 240 ÷ 5?

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.The strategy of separating a number into its individual units of value is commonly known as?

1/5

Q2.Half of 24 is also the same as:

2/5

Q3.The bar model below is used to help divide or multiply numbers. What number should be placed in the top white boxes?

3/5

Q4.Which of the following number sentences will help you to solve the calculation 25 x 8?

4/5

Q5.Which derived fact helps me to mentally solve 240 ÷ 5?

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 Derived Facts to Multiply Mentally Quiz

We covered a wide range of strategies for mental arithmetic during the lesson today which will allow you to be flexible and efficient when faced with different problems and tasks. Now it is time to put your knowledge to the test! Remember to read all questions carefully.

Q1.Which of the following methods for answering a multiplication questions is NOT a mental strategy?

1/5

Q2.Today we discussed distributive law in relation to multiplication. But which of the following number sentences does NOT correctly represent distributive law?

2/5

Q3.Which of the following representations would be efficient for the calculation 317 x 23?

3/5

Q4.For which of these calculations would you consider using a mental strategy and NOT a written method?

4/5

Q5.Which calculation do the dienes represent?

5/5

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

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

# Using Derived Facts to Multiply Mentally Quiz

We covered a wide range of strategies for mental arithmetic during the lesson today which will allow you to be flexible and efficient when faced with different problems and tasks. Now it is time to put your knowledge to the test! Remember to read all questions carefully.

Q1.Which of the following methods for answering a multiplication questions is NOT a mental strategy?

1/5

Q2.Today we discussed distributive law in relation to multiplication. But which of the following number sentences does NOT correctly represent distributive law?

2/5

Q3.Which of the following representations would be efficient for the calculation 317 x 23?

3/5

Q4.For which of these calculations would you consider using a mental strategy and NOT a written method?

4/5

Q5.Which calculation do the dienes represent?

5/5

# Lesson summary: Using derived facts to multiply mentally

## 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