Explain how to use the associative law to multiply efficiently
I can explain how to use factorisation and the associative law to multiply efficiently.
Explain how to use the associative law to multiply efficiently
I can explain how to use factorisation and the associative law to multiply efficiently.
Lesson details
Key learning points
- Multiplication can be simplified by factorising one of the factors.
- Look at the factors to identify which are composite numbers.
- Composite numbers can be factorised.
- Multiplication is commutative.
- Factors can be grouped in different ways and the product remains the same.
Common misconception
Pupils can identify factors of a 2-digit number but do not consider efficiency when multiplying.
Draw attention to factor pairs and those which result in easier calculations e.g. pupils often find multiplying by 4 or 5 easier than 7, or can apply doubling when multiplying by 2
Keywords
Associative law - 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.
Composite number - A composite number is an integer with more than two factors. All integers greater than 1 are either composite or prime.
Equipment
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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