Math Elementary arithmetic Commutative law

# Commutative law

The commutative law (commutative property) applies in addition and multiplication.

## The commutative law of addition

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### Remember

In a sum, it is allowed to exchange the summands without changing the value of the sum at the same time.
$a+b=b+a$

### Examples

• $8+9=17$ and $9+8=17$
$8+9=9+8$

• $3+(-9)=-6$ and $(-9)+3=-6$
$3+(-9)=(-9)+3$

## The commutative law of multiplication

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### Remember

In a product, it is allowed to exchange the factors without changing the value of the product at the same time.
$a \cdot b=b \cdot a$

### Examples

• $5\cdot6=30$ and $6\cdot5=30$
$5\cdot6=6\cdot5$

• $(-9)\cdot8=-72$ and $8\cdot(-9)=-72$
$(-9)\cdot8=8\cdot(-9)$