Unit 20 Section 3 : Multiplying Fractions
To multiply two fractions, we multiply the two numerators (top numbers) together to get the new numerator, and we multiply the two denominators (bottom numbers) together to get the new denominator.
Sometimes some cancelling-down can happen before the numerators and denominators are multiplied together.
If there are whole numbers or mixed numbers, these can be converted into top-heavy fractions and multiplied in the same way.
At this stage we can cancel numerators with denominators if they are both divisible by the same number.
In a similar way 3 and 9 can be cancelled as they are both divisible by 3.
Now the fractions can be multiplied:
NOTE: You can only cancel a numerator with a denominator, not two numerators or two denominators.
Now the multiplication can be pre-cancelled:
Finally we can do the multiplication:
NOTE: Some people prefer to answer this type of question by dividing 15 by 5 to get one fifth of 15 (which is 3)
If there is a mixed number in the question, it must be converted into a top-heavy fraction before multiplying.
We can now pre-cancel and carry out the multiplication as normal:
Practice QuestionWork out the answer to each of these questions then click on the button marked to see whether you are correct.
ExercisesWork out the answers to the questions below and fill in the boxes. Click on the button to find out whether you have answered correctly. If you are right then will appear and you should move on to the next question. If appears then your answer is wrong. Click on to clear your original answer and have another go. If you can't work out the right answer then click on to see the answer.
Produced by A.J.Reynolds April 2011