In this lesson, we will explain and model mental strategies for doubling and halving by using our understanding of multiplication and division. We will also use our doubling and halving strategies to multiply and divide by four and eight. By the end of this lesson, we would hope that everyone will be confident in explaining how to multiply and divide by four and eight by using strategies of doubling and halving.

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Look at the value represented by the place value grid below. If I multiply the number by 100, what will the new product be?

2,400,000

24,000

Correct answer: 240,000

240,000

Q2.

In mathematics, we use the term 'product' regularly. Look at the following calculation and identify which of the numbers listed would be classified as the product. 30 x 2 x 10 = 600

10

2

30

Correct answer: 600

600

Q3.

Which of the facts can I derive from the representation below?

2 x 40 = 80

20 x 4 = 80

80 ÷ 2 = 40

Correct answer: All of the above

All of the above

None of the above

Q4.

Using the area model below, can you identify which of the number sentences is correct?

Correct answer: 30 x 40 = 3 x 4 x 10 x 10

30 x 40 = 3 x 4 x 10 x 10

30 x 40 = 3 x 40 x 100

30 x 40 = 30 x 4 x 1

30 x 40 = 30 x 40 x 100

Q5.

When multiplying and dividing, we regularly use the terms 'greater than' and 'less than'. Which of the following statements has used the symbols incorrectly?