Use knowledge of the distributive law to solve two-part subtraction problems
I can use knowledge of the distributive law to solve two part subtraction problems efficiently.
Use knowledge of the distributive law to solve two-part subtraction problems
I can use knowledge of the distributive law to solve two part subtraction problems efficiently.
Lesson details
Key learning points
- Partitioning a factor is called distribution or using the distributive law.
- Partitioned factors can be subtracted to simplify two-part subtraction problems.
- Eight 9s subtract three 9s is equal to five 9s.
Common misconception
When looking at an expression such as 5 × 6 − 5 × 3 children might be tempted to subtract first leading to an expression like this: 5 × 1 × 3
Ensure that you support the equation with the arrays so that pupils understand where the multiplication expressions come from and they can match the partial products to the arrays.
Keywords
Common factor - When we compare lists of factors of two or more numbers, any factors that are the same are the common factors.
Distributive law - The distributive law says that multiplying a number by a group of numbers added together is the same as doing each multiplication separately.
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
6 Questions
Exit quiz
6 Questions
4 × 5
3 × 5
6 × 4