Multiplying & Dividing Fractions (Cambridge (CIE) IGCSE International Maths)
Revision Note
Written by: Naomi C
Reviewed by: Dan Finlay
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Multiplying Fractions
How do I multiply two fractions?
Cancel any factors that are common to both the numerator and the denominator
The common factors could be in either of the fractions
Multiply
Multiply the numerators
Multiply the denominators
Cancel any common factors again if possible
How do I multiply two fractions if one is a mixed number?
Always convert mixed numbers into improper fractions before multiplying
Convert improper fractions back into mixed numbers at the end if required
Worked Example
Find .
The 15 and 25 can be cancelled before multiplying
Multiply the numerators together and the denominators together
There is no further cancelling that can be done
Write down the fraction
Dividing Fractions
How do I divide two fractions?
Flip the second fraction and change ÷ into × ”
becomes
The 'flipped' fraction is called a reciprocal fraction
Cancel any factors that are common to both the numerator and the denominator
Multiply the fractions
Multiply the numerators
Multiply the denominators
Cancel any common factors again if possible
How do I divide two fractions when one of them is a mixed number?
Always convert mixed numbers into improper fractions before dividing
Convert improper fractions back into mixed numbers at the end if required
Examiner Tips and Tricks
Remember “flip’n’times"
When dividing fractions you are multiplying by the reciprocal
Worked Example
Divide by , giving your answer as a mixed number.
Rewrite as an improper fraction
Turn the division into a multiplication
'Flip' the second fraction and turn ÷ into ×
Cancel a factor of 4 from the numerators and denominators
Multiply the fractions
Rewrite as a mixed number
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