Grade 8 → Number Systems → Properties of Real Numbers ↓
Commutative Property
The commutative property is a fundamental principle in mathematics that applies to addition and multiplication. This property states that the order in which two numbers are added or multiplied has no effect on the result. It is a basic but powerful concept that helps simplify many mathematical problems.
Commutative property of addition
Let's start with addition. When you have two numbers, say a
and b
, the commutative property of addition tells us that:
a + b = b + a
In other words, the sum will remain the same even if you change the order of the numbers.
Examples of the commutative property of addition
Let's look at some examples to understand this better:
Consider numbers 3 and 5:
3 + 5 = 8
Now change the order:
5 + 3 = 8
As you can see, 3 + 5
gives the same result as 5 + 3
The sum in both cases is 8.
Here's another example with large numbers. Take 21 and 14:
21 + 14 = 35
Change the numbers:
14 + 21 = 35
Again, the sum remains 35. Whatever the order of addition, the result does not change.
Commutative property of multiplication
Just like addition, the commutative property applies to multiplication as well. For any two numbers a
and b
:
a × b = b × a
This means that changing the order of the factors does not change the product.
Examples of commutative property of multiplication
Let's look at some examples of multiplication:
Consider the numbers 4 and 7:
4 × 7 = 28
If we change these to:
7 × 4 = 28
Whatever the order, the product remains 28.
Here's another example with different numbers, like 9 and 6:
9 × 6 = 54
Now reverse the numbers:
6 × 9 = 54
The result is also 54. We learn that the order of multiplication does not affect the result.
Why is commutative property important?
The commutative property is important because it allows us to rearrange numbers when solving problems, making calculations easier and more flexible. Understanding and applying this property can save a lot of time, especially when dealing with complex problems or mental arithmetic.
Imagine you are adding several numbers together. You can group and rearrange them as needed:
(2 + 3) + 5 = 2 + (3 + 5) = 10
By rearranging the numbers, you can often simplify the process to make mental calculations quicker.
Visual example
Add
As shown in the figure, 3 + 5
and 5 + 3
both add up to 8, which shows the commutative property.
Multiplication
Similarly, the multiplication example of 4 × 7
and 7 × 4
gives the result 28, which shows the commutative property.
Limitations of exchangeable assets
It is important to note that the commutative property does not apply to subtraction or division. For example:
In subtraction:
7 - 3 ≠ 3 - 7
The results differ because the subtraction depends on the order.
In the division:
12 ÷ 4 ≠ 4 ÷ 12
Again, the results are different, indicating that the division is also non-commutative.
Conclusion
The commutative property is a fundamental aspect of mathematics that simplifies arithmetic and aids in understanding more complex mathematical concepts. While this property applies to addition and multiplication, it is important to remember that it does not apply to subtraction or division. Recognizing and taking advantage of the commutative property can streamline calculations and problem-solving, allowing you to approach mathematics with greater confidence and flexibility.