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Year 5

Predicting the size of a product

I can explain how to use the size of one number in a multiplication to predict the size of the product.

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New
New
Year 5

Predicting the size of a product

I can explain how to use the size of one number in a multiplication to predict the size of the product.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. If one factor is made ___ times the size and the other factor remains the same, the product will be ___ times the size.
  2. When a number is multiplied by a value less than one, the product is smaller than the original number.
  3. When a number is multiplied by a value greater than one, the product is greater than the original number.

Common misconception

Children may think that multiplication always makes things larger. Children may scale incorrectly.

When a number is multiplied by a value less than 1, the product is smaller than the original number - multiplication doesn't always make things larger. Compare numbers: if one factor is made ___ times the size, the product will be ___ times the size.

Keywords

  • Product - The product is the result of two or more numbers multiplied together.

  • Factor - Factors are integers that are multiplied together to get a product.

Refer to keyword definition - a factor is an integer so decimal fractions cannot be considered factors. Provide children with scaffolded support it they are not confident with their times-tables.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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Starter quiz

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6 Questions

Q1.
Match the number to its written representation.
Correct Answer:seven tenths,0.7

0.7

Correct Answer:nine tenths,0.9

0.9

Correct Answer:seven ones,7

7

Correct Answer:seven hundredths,0.07

0.07

Correct Answer:nine hundredths,0.09

0.09

Q2.
Complete the equations by matching the expression with its missing part.
Correct Answer:5 × ___ = 25,5

5

Correct Answer:5 × ___ = 30,6

6

Correct Answer:5 × ___ = 40,8

8

Correct Answer:5 × ___ = 55,11

11

Correct Answer:5 × ___ = 35,7

7

Q3.
Match the expression to its product.
Correct Answer:9 × 9,81

81

Correct Answer:9 × 4,36

36

Correct Answer:9 × 1,1

1

Correct Answer:9 × 5,45

45

Correct Answer:9 × 6,63

63

Q4.
Match the expression to its product.
Correct Answer:9 × 10,90

90

Correct Answer:9 × 100,900

900

Correct Answer:9 × 1,000,9,000

9,000

Correct Answer:19 × 10,190

190

Correct Answer:19 × 100,1,900

1,900

Q5.
Match the expression to its product.
Correct Answer:8 × 0.1,0.8

0.8

Correct Answer:8 × 0.01,0.08

0.08

Correct Answer:18 × 0.1,1.8

1.8

Correct Answer:18 × 0.01,0.18

0.18

Correct Answer:108 × 0.01,1.08

1.08

Q6.
Which of the following would make this calculation correct? 43 > 8 × ___
Correct answer: 5
6
7
8

Exit quiz

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6 Questions

Q1.
Use the fact that 9 × 8 = 72, to match the expressions to their product.
Correct Answer:9 × 80,720

720

Correct Answer:9 × 800 ,7,200

7,200

Correct Answer:9 × 0.8,7.2

7.2

Correct Answer:9 × 0,0

0

Correct Answer:9 × 0.08,0.72

0.72

Q2.
If 6 × 72 = 432, what does 6 × 0.72 equal?
4,320
432
43.2
Correct answer: 4.32
0.432
Q3.
True or False? 13 × 0.9 will have a product that is smaller than 13
Correct answer: True
False
Q4.
Match the expression with its missing symbol < > or =
Correct Answer:6 × 0.7 ___ 6,<

<

Correct Answer:6 × 1.7 ___ 6,>

>

Correct Answer:6 × 1 ___ 6,=

=

Q5.
Which of the following would make this calculation correct? 3.4 > 0.9 × ___
Correct answer: 3
4
5
6
Q6.
Which of the following will have a product greater than the original number being multiplied?
6 × 0.2
6 × 1
6 × 0
Correct answer: 6 × 1.2
Correct answer: 6 × 3.5