Multiplying Fractions
If you are able to multiply whole numbers together then you will be able to multiply fractions. Here is how it is done.
Step One: Multiple the top numbers (or numerators) of the fractions together and write down the answer as the new numerator.
Step Two: Multiple the bottom numbers (or denominators) of the fractions together and write down the answer as the new denominator.
Step Three: If it is possible, simplify the fraction.
Now, we will try an example.
Example 1: 1/2 x 1/2
Step One:
The numerator of the first fraction is 1. The numerator of the second fraction is 1.
We know that 1 x 1 = 1, so the new numerator will be 1.
1/2 x 1/2 = (1 x 1)/? = 1/?
Step Two:
The denominator of the first fraction is 2. The denominator of the second fraction is 2.
We know that 2 x 2 = 4, so the new denominator will be 4.
1/2 x 1/2 = 1/ (2 x 2) = 1/4
Step Three:
Since the fraction 1/4 is already in lowest terms we are done.
Therefore, we have found that 1/2 x 1/2 = 1/4.
Now you try one.
3/4 x 1/4 =
Note: When we are multiplying fractions together, we do not need the denominators to be the same like we do for addition.
Here are some more examples of multiplying fractions together.
1/2 x 3/4 = (1×3) / (2 x 4) = 3/8
2/3 x 7/2 = (2 x 7) / (3 x 2) = 14/6 = 7/3
Dividing Fractions
Now that we know how to multiply fractions together, we will be able to divide fractions as well. Dividing fractions is the same as multiplying the first fraction by the reciprocal of the second fraction.
Do you know that the reciprocal of a fraction is? If not, don’t worry.
In order to take the reciprocal of a fraction, we switch the roles of the numerator and the denominator.
Here are some quick examples:
The reciprocal of 2/3 is 3/2.
The reciprocal of 4/5 is 5/4.
The reciprocal of 1/7 is 7/1 = 7.
Now that we know what the reciprocal of a fraction is, let’s look at how we can change a division question with fractions which we might not be able to answer into a multiplication question using fractions which we will be able to answer.
Remember: Dividing fractions is the same as multiplying the first fraction by the reciprocal of the second fraction.
Here are some examples:
1/4 ÷ 2/4 = 1/4 x 4/2
2/3 ÷ 2/4 = 2/3 x 4/2
2/6 ÷ 3/5 = 2/6 x 5/3
Now, we will work all the way through an example of how to divide fractions.
Example 2: 4/5 ÷ 1/3
Step One: Change the division question into a multiplication question, by multiplying by the reciprocal.
4/5 ÷ 1/3 = 4/5 x 3/1
Step Two: Multiply the numerators together to get the new numerator.
4/5 x 3/1 = (4 x 3)/ ? = 12/?
Step Three: Multiply the denominators together to get the new denominator.
4/5 x 3/1 = 12/ (5 x 1) = 12/5
Step Four: If it is possible, simplify the fraction.
The fraction 12/ 5 is already in simplest form.
Now it is your turn again.
What is 3/2 ÷ 1/4?
This was written for you by Mia, one of the tutors with Test Prep Academy.