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Year 7

Multiplying with decimals

I can generalise and fluently use written multiplication strategies to calculate accurately with decimals.

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New
New
Year 7

Multiplying with decimals

I can generalise and fluently use written multiplication strategies to calculate accurately with decimals.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. The factorising multiples of 10 strategy can be used.
  2. With multiplication it is important to consider the magnitude of the product.
  3. Similar calculations can be used to help reason about a product.

Common misconception

When pupils multiply decimals, they use the column method and align the decimal points.

If the column method is used, encourage integer multiplication and use of powers of 10 to adjust the answer to the original calculation.

Keywords

  • Factorising - Factorising means to express a term as the product of its factors.

Without calculating the answer, pose questions to pupils or the class to verbalise the integer multiplication with powers of 10 e.g 3.4 x 5.6 = 34 x 0.1 x 5.6 x 0.1
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).

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Starter quiz

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6 Questions

Q1.
A is a term which exactly divides another term.
Correct Answer: factor, Factor
Q2.
Match the multiplication of these integers with their answers
Correct Answer:$$6\times4$$ ,24

24

Correct Answer:$$6\times5$$ ,30

30

Correct Answer:$$9\times2$$ ,18

18

Correct Answer:$$8\times4$$ ,32

32

Q3.
Complete the calculation: $$6\times$$ $$= 600$$
Correct Answer: 100, hundred
Q4.
Divide 1 into 10 equal parts. What does each part represent as a decimal?
0.00001
0.001
Correct answer: 0.1
1
Q5.
Divide 1 into 100 equal parts. What does each part represent as a decimal?
0.1
Correct answer: 0.01
0.001
0.0001
Q6.
Without using a calculator, work out: $$2.4+1.28+0.3+0.13=$$
Correct Answer: 4.11

Exit quiz

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6 Questions

Q1.
A __________ is the result of two or more numbers multiplied together.
Correct answer: product
factor
multiple
prime
Q2.
Which of these is equivalent to 6.34?
$$634\times0.1$$
Correct answer: $$634\times0.01$$
$$634\times0.001$$
$$634\times10$$
Q3.
Dividing by 1000 is equivalent to __________
$$\times0.1$$
$$\times0.01$$
Correct answer: $$\times0.001$$
$$\times0.0001$$
Q4.
Which of these is equivalent to $$4.56\times2.3$$?
$$456\times23\times0.1$$
$$456\times23\times0.01$$
Correct answer: $$456\times23\times0.001$$
$$456\times23\times10$$
Q5.
Work out: $$5.8\times2.9=$$
Correct Answer: 16.82, 16.820
Q6.
Using your knowledge on identifying a reasonable answer and without working out, match the calculation to the correct answer.
Correct Answer:$$2.4\times8.4$$ ,20.16

20.16

Correct Answer:$$2.9\times2.5$$ ,7.25

7.25

Correct Answer:$$11.3\times3.1$$ ,35.03

35.03

Correct Answer:$$5.7\times0.2$$ ,1.14

1.14