Explain how to use the factor pairs of 100 to solve calculations efficiently
Lesson details
Learning outcome
I can explain how to use the factor pairs of 100 to solve calculations efficiently.
Key learning points
- Scales are often marked in factors of 100
- Rearranging calculations to make use of factors of 100 can simplify them
Keywords
Factor - Factors are whole numbers which exactly divide another whole number.
Commutative - The commutative law states that you can write the values of a calculation in a different order without changing the calculation; the result is the same. It applies for addition and multiplication.
Associative - The associative law states that it doesn't matter how you group or pair values (i.e. which we calculate first), the result is still the same. It applies for addition and multiplication.
Common misconception
Pupils decompose the wrong factor therefore find it difficult to find a pair of factors that are equal to 100
Scaffold pupil's thinking when they begin to tackle a 2 digit by 2 digit calculation. Encourage them to ask questions of the numbers, for example: 'Is one of the numbers I have to start with a factor of 100?'
Teacher tip
Be sure to make connections back to pupils' learning in year 3 when they explored the common partitions of 100. This will be helpful as they make connections between the representations and how these are recorded as multiplicative equations.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.A factor is:
Q2.Write down the missing factor from this factor bug.
Q3.Which parts of a division equation can represent factors?
Q4.Tick the equations that are true.
Q5.Apply the associative law to complete this calculation. 36 × 2 × 5 =
Q6.Tick the calculation that could be represented as 5 × 2 × 31
Assessment exit quiz
6 Questions
Q1.Tick the factor pairs of 100
Q2.Write down the missing factor in this factor bug.
Q3.What is the temperature shown on the thermometer?
Q4.Match the equation to the factors pairs that would be best used to help solve the calculations.
2 and 50
4 and 25
5 and 20
Q5.Tick the three factor expression that could be represented by this equation. 64 × 25 = ___
Q6.Tick the equations that are true.
To help you plan your 5 maths lesson on: Explain how to use the factor pairs of 100 to solve calculations efficiently, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 5 maths lesson on: Explain how to use the factor pairs of 100 to solve calculations efficiently, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 2 maths lessons from the Use common factors and multiples to solve calculations efficiently unit, dive into the full primary maths curriculum, or learn more about lesson planning.