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Good knowledge of multiplying Fractions!




Before you start this lesson on multiplying fractions, I recommend that you become familiar with the multiplication table



Multiplying fractions is very easy. However, I would like to introduce the topic with a challenging example.

Say that you bought a medium pizza and your pizza has 8 slices.

If someone eats half of your pizza, or 4 slices, you are left with
4 / 8

From the illustration below, you can also see that the leftover is the same as
1 / 2
half


If you decide that you are only going to eat 1 slice out of the 4 slices remaining, you are eating
1 / 4
of the leftover

Remember that the leftover is
1 / 2

You can also argue that you only ate 1 slice out of 8 slices or
1 / 8

one-eigth


Thus, we can see that eating 1/4 of 1/2 is the same as eating 1/8

Another way to get  
1 / 8
 is to perform the following multiplication:

1 / 4
×
1 / 2
=
1 / 8


We get this answer by multiplying the number on top (numerator): 1 × 1 = 1

and by multiplying the number at the bottom (denominator) 4 × 2 = 8

This is an interesting result, but all you need to remember is the following:

When you multiply fractions, multiply the numerators together

Then multiply the denominators together.

Notice also that the word 'of' means multiplication

More examples

3 / 5
×
4 / 7
=
12 / 35


Sometimes, it is a good idea to simplify the fractions before multiplying.

Take a look at the following example:

10 / 20
×
3 / 15


10 / 20
 
can be simplified as  
1 / 2


Divide the numerator and the denominator by 10



3 / 15
 
can be simplified as  
1 / 5


Divide the numerator and the denominator by 5



This way, it is easier to do the multiplication to get  
1 / 10


Related topics:

Multiplying mixed numbers

Multiply fractions calculator





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