Year 5
Year 5

Doubling and halving strategies

Lesson details

Key learning points

  1. 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.

Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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5 Questions

Q1.
Look at the value represented by the place value grid below. If I multiply the number by 100, what will the new product be?
An image in a quiz
2,400,000
24,000
Correct answer: 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
Q3.
Which of the facts can I derive from the representation below?
An image in a quiz
2 x 40 = 80
20 x 4 = 80
80 ÷ 2 = 40
Correct answer: All of the above
None of the above
Q4.
Using the area model below, can you identify which of the number sentences is correct?
An image in a quiz
Correct answer: 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?
10 x 3 x 2 = 15 x 4
Correct answer: 1731 < 1713
234 > 219
28194 < 28914

5 Questions

Q1.
The strategy of separating a number into its individual units of value is commonly known as?
Approximation
Guessing
Correct answer: Partitioning
Rounding
Q2.
Half of 24 is also the same as:
240 ÷10
Correct answer: 48 ÷ 4
72 ÷ 3
96 ÷ 2
Q3.
The bar model below is used to help divide or multiply numbers. What number should be placed in the top white boxes?
An image in a quiz
12
Correct answer: 15
40
6
Q4.
Which of the following number sentences will help you to solve the calculation 25 x 8?
100 x 4
250 x 80
Correct answer: 50 x 4
50 x 8
Q5.
Which derived fact helps me to mentally solve 240 ÷ 5?
120 ÷ 10
120 x 10
48 ÷ 10
Correct answer: 48 x 10