Elevise
  • Home
  • GCSE Maths
  • GCSE Science
  • Membership
Back to Edexcel Fractions (F) Home
1.3 L) Dividing Fractions
Whenever we are dividing one fraction by another fraction, we keep the first fraction the same, flip the second fraction (the fraction that we are dividing by) and change the division sign to a multiplication sign. The flipping of the second fraction means that the original numerator becomes the new denominator and the original denominator becomes the new numerator. 
 
An easy way to remember this is to use KFC, Keep the first fraction the same, Flip the second fraction and Change the division sign to a multiplication sign.
 
If we have any mixed numbers in the question, we need to convert them into improper fractions first (example 2 will require us to do this).
 
Let’s have a few examples. 

Example 1

Complete the calculation below.

Picture

According to KFC, we keep the first fraction the same, flip the second fraction and change the division sign to a multiplication sign. The calculation becomes:

Picture

We now multiply across like normal; we multiply the two numerators and multiply the two denominators.

Picture

We now need to check if we can simplify our answer and give it as a mixed number. The numerator of our fraction is less than the denominator and this means that we do not need to change the fraction into a mixed number. Also, it cannot be simplified because there are no common factors between 8 and 15.

 

Therefore, the final answer for this question is 8/15.


Example 2

Complete the calculation below.

Picture

Both of the components in the calculation above are given as mixed numbers. Therefore, the first step in answering this question is to convert them from mixed numbers to improper fractions. We do this by multiplying the whole number by the denominator of the fraction part of the mixed number and then adding this number to the numerator of the fraction part of the mixed number. The denominator of the fraction stays the same.

 

So, for the first component, we will be multiplying 5 (the whole number) by 3 (the denominator of the fraction), which gives us 15. The next step is to add the original numerator in the fraction to the number that we have just obtained; 15 + 2. The first component as an improper fraction is 17/3.

Picture

We do the same for the second component. We multiply the number of wholes (1) by the denominator (4), which gives us 4. We then add this to the numerator of the fraction part of the mixed number (3), which gives 7. Therefore, the second component as a mixed number is 7/4.

Picture

The calculation as two improper fractions is:

Picture

We are now ready to use KFC; we keep the first fraction the same, flip the second fraction and change the sign from a divide to a multiply. The calculation becomes:

Picture

We are now able to multiply straight across.

Picture

We now need to simplify and convert the fraction into a mixed number. Let’s convert the fraction into a mixed number first. We do this by seeing how many times the denominator (21) goes into the numerator (68). 21 goes into 68, 3 full times with a remainder of 5. The fraction becomes:

Picture

We now check the fraction to see if it can be simplified. There are no common factors between 5 and 21 meaning that the fraction is already in its simplest form. Therefore, the answer to this question is 3 5/21.

Home
GCSE Maths
GCSE Science
Membership
Tuition
United Kingdom
[email protected]
  • Home
  • GCSE Maths
  • GCSE Science
  • Membership