Mental calculations can be performed faster by reorganising calculations into an easier format.
The commutative property means that the order in which you multiply or add numbers will have no effect on the answer.
Demonstrate the commutative law with .
Reorder the numbers to .
Note: The commutative property can be applied even if there are more than two numbers being multiplied together.
Factor pairs are two whole numbers which multiply to give the original number. Factor pairs can be used to break up a multiplication into easier steps.
How many factor pairs doeshave?
Find all the whole numbers which multiply to give .
There are factor pairs for .
Note: The commutative property means the factor pairs can be written in the opposite order.
can be split into and . Use this to work out .
Multiply the numbers in an order you find easy.
Note: is a prime number which means its only factor pair is and .
Question: What are factor pairs?
Answer: Factor pairs are two whole numbers which multiply to give the original number.
Question: What is the commutative property?
Answer: The commutative property means that the order in which numbers are multiplied has no effect on the answer.