Multiplying fractions is in the Primary 5 Four Operations of Fractions chapter. The lesson film is the one Mathweave teaches this skill with in Primary 6, and the practice set below is written for Primary 5.
Lesson video, with the working
Multiplying fractions
3 min 13 s
The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.
What is one half of one third? Fold a strip twice to see.
One half of one third is 1/6.
Ans: {1|6}
Example 1
Work out three quarters times two fifths. Give the answer in its simplest form.
Three quarters times two fifths is 3/10.
Ans: {3|10}
How to solve it
Read of as multiply: one half of one third is one half times one third.
Fold a strip into 3 parts, then fold the other way into 2. That makes 6 equal parts, and one piece is one sixth.
Multiply the tops and multiply the bottoms: 1 times 1 over 2 times 3 is one sixth.
Cancel a common factor first. In three quarters times two fifths, the 4 and the 2 share a factor of 2.
Multiply what is left: 3 times 1 over 2 times 5 is three tenths, already in its simplest form.
To multiply fractions, multiply the top numerator, then multiply the bottom denominator. Cancel any common factor, so that the answer is in its simplest form. A fraction of a fraction is a multiplication, every time.
Practice questions with worked solutions
Question 1 is free to try. The other 3 open in the free trial, each with its full working.
How do you work through P5 multiplying fractions questions?
This page teaches the Primary 5 outcomes on multiplying fractions: a proper fraction by a proper or improper fraction, and two improper fractions.
What your child learns here
This page teaches the Primary 5 outcomes on multiplying fractions: a proper fraction by a proper or improper fraction, and two improper fractions. It links the word 'of' to multiplication and shows why the answer can be smaller than both fractions.
'One half of three fifths' means one half × three fifths.
Multiply the numerators, then multiply the denominators.
Cancel a common factor between a numerator and a denominator first, so the numbers stay small.
Multiplying by a proper fraction gives a smaller answer; multiplying by an improper fraction gives a larger one.
Give the answer in simplest form, as a mixed number when it is improper.
Does the answer make sense?
When your child multiplies by a fraction greater than 1, the result must be bigger than the other number, and by a fraction less than 1 it must be smaller. So 6 times seven quarters must come out above 6, while 9 times four sevenths must come out below 9.
How to practise these questions
Basic questions train multiplying with fractions and simplifying the product before writing the answer. Intermediate questions multiply two improper fractions together, cancelling before the answer is written as a mixed number. If the product will not simplify neatly, watch that question's solution film, then try it again later from Revision.
Questions parents ask
Which fraction multiplications are in the Primary 5 syllabus? Primary 5 covers multiplying a proper or improper fraction and a whole number, a proper fraction and a proper or improper fraction, two improper fractions, and a mixed number and a whole number.
Why does multiplying fractions make the answer smaller? Multiplying by a proper fraction takes part of an amount. One half of three quarters is less than three quarters, so the answer must be smaller.
Should my child cancel before or after multiplying? Either gives the same answer. Cancelling first keeps the numbers small, which leaves less to simplify at the end.
