Primary 4 · Number & Algebra

P4 fractions

In P4, your child turns improper fractions into mixed numbers, finds a fraction of a set, and adds and subtracts fractions with different denominators. The adding is where most marks go: the pieces have to be the same size first.

Taught in: Term 2
Syllabus: 3 skills
Usual slip: Adds across

Updated 13 October 2026

Eleven quarters on a number line, ending at two and three quarters

What your child learns in P4 fractions

Three skills, each with what it looks like on a worksheet.

Follows the latest (2026) MOE syllabus

See the syllabus wording

mixed numbers, improper fractions and their relationship
fraction as part of a set
adding and subtracting fractions with denominators of given fractions not exceeding 12 and not more than two different denominators

Mixed numbers and improper fractions

An improper fraction has a numerator equal to or bigger than its denominator. Eleven quarters make 2 wholes with 3 quarters left, so it is two and three quarters. To change it, divide: 11 ÷ 4 = 2 R 3.

Point	Value
Point 1	2.75

Eleven quarters lands on two and three quarters

A fraction of a set

To find two thirds of 12 marbles, split the 12 into 3 equal groups of 4. One third is 1 group, so two thirds is 2 groups, which is 8 marbles.

Two thirds of 12 is 8

Adding and subtracting fractions

Make the pieces the same size first, then add or take away only the numerators. Two thirds is four sixths, so two thirds and one sixth make five sixths. The denominator does not change.

Four sixths and one sixth make five sixths

Key facts and formulas

Term 2

Mixed number to improper fractionEach whole is 5 fifths. Count all the fifths.fifths → $2 \times 5 + 3 =$ $13$ $2\frac{3}{5} =$ $\frac{13}{5}$
Improper fraction to mixed numberDivide the numerator by the denominator. What is left over is the fraction. $7 \div 3 =$ $2\text{ R }1$ $\frac{7}{3} =$ $2\frac{1}{3}$
Fraction of a setCut the set into equal units, one for each part. Find 1 unit first.1 unit → $15 \div 5 =$ $3$ 3 fifths of 15 → $3 \times 3 =$ $9$
Add or subtract fractionsMake the denominators the same, then add or take away the numerators. $\frac{2}{3} + \frac{1}{4} =$ $\frac{8}{12} + \frac{3}{12} =$ $\frac{11}{12}$ $\frac{7}{10} - \frac{2}{5} =$ $\frac{7}{10} - \frac{4}{10} =$ $\frac{3}{10}$

Words to know

Denominator: The bottom number. It names the size of the pieces, such as quarters or sixths.
Numerator: The top number. It counts how many of those pieces there are.
Improper fraction: A fraction whose numerator is equal to or bigger than its denominator.
Mixed number: A whole number and a fraction together, such as two and three quarters.
Equivalent fractions: Fractions of the same size written with different numbers. One half is three sixths.

The sentence that costs the mark

Find the value of $\frac{1}{2} + \frac{1}{3}$ .

Cut both into sixths so the pieces match

What the working usually does

add across $\frac{1}{2}+\frac{1}{3}$ = $\frac{2}{5}$

Adds the tops and the bottoms: 1 + 1 over 2 + 3. It lands on a tidy fraction, so the working looks finished.

What the question asked

same size $\frac{1}{2}+\frac{1}{3}$ = $\frac{5}{6}$

Makes the pieces the same size first, sixths, then adds only the tops: 3 sixths and 2 sixths make 5 sixths.

Adding straight across is how whole numbers work, so nothing looks careless. But 2/5 is smaller than 1/2, and adding something to a half cannot make it smaller.

The same P4 fractions question, worked properly

Lah works through it the way she does every question in StudyLah: one step at a time, marking the picture as she goes.

Add $\frac{3}{10}$ and $\frac{4}{5}$ . Write your answer as a mixed number.

Step 1 of 5▌

Tenths and fifths are different sizes, so they cannot be added yet. Adding straight across would give $\frac{7}{15}$ , and that is wrong.
10 is 2 × 5, so cut 1 whole into 10 equal units, the tenths. Multiply the top and bottom by 2 to get an equivalent fraction: $\frac{4}{5}$ = $\frac{8}{10}$ .
Now add the numerators and keep the tenths: $\frac{3}{10}$ + $\frac{8}{10}$ = $\frac{11}{10}$ .
$\frac{11}{10}$ is more than 1 whole. As a mixed number, 10 tenths make 1 whole and 1 tenth is left: $\frac{11}{10}$ = $1\frac{1}{10}$ .
So the answer is $1\frac{1}{10}$ .

Every question in StudyLah comes with a walkthrough like this one.

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Three quick P4 fractions questions

Try them together, then tap to check.

Question 1

How many thirds are there in $5\frac{2}{3}$ ?

Show answer

Answer17. Each whole is 3 thirds, so 5 wholes are 15 thirds. 15 + 2 = 17 thirds.

Question 2

There are 96 pupils in a hall. $\frac{5}{8}$ of the pupils are girls. How many boys are there?

Show answer

Answer36. 1 unit is 96 ÷ 8 = 12. The boys are the other 3 units, so 3 × 12 = 36.

Question 3

What is the sum of $\frac{5}{8}$ and $\frac{1}{4}$ ?

Show answer

Answer $\frac{7}{8}$ . $\frac{1}{4}$ = $\frac{2}{8}$ , so $\frac{5}{8}$ + $\frac{2}{8}$ = $\frac{7}{8}$ . Adding across would give $\frac{6}{12}$ .

Helping at home

How to tell it has clicked

Ask your child whether one half plus one third can be smaller than one half. If they say no, ask them to check their answer against that. A 2/5 fails the check on sight.

Then ask what the bottom number means. If they say it is the size of the pieces, they have the idea that stops the slip.

Try this tonight

Cut one slice of bread into halves and another into thirds. A half and a third do not stack into a neat piece until both are cut into sixths.

Ask why "two out of five" cannot be right when you started with a whole half. Then cut and count the sixths together: three and two make five.

Before and after P4 fractions

Builds on
Primary 3 Fractions
Compares, simplifies, adds and subtracts fractions
You are here
Primary 4 Fractions
Adds fractions once the pieces match
Head Start
The P4 to P5 Maths jump: what to revise before P5
One of three P4 topics to revise before P5 Term 1
Leads to
Primary 5 Fractions and Division
Takes a fraction of what is left

The methods your child will use here

More in Primary 4

Struggling with the working rather than the topic itself? How to help your child with problem sums

See how your child is doing on this topic

StudyLah marks each step separately, so you can see whether it was the setup or the arithmetic that cost the mark.

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