Primary 5 · Number & Algebra

P5 percentage

Percent means out of 100. In P5, your child writes a part of a whole as a percentage, changes fractions and decimals into percentages, finds a percentage of an amount, and works out discount, GST and annual interest.

Taught in: Term 3
Syllabus: 4 skills
Usual slip: Moves the point once

Updated 10 October 2026

A hundred-square with 25 of its 100 squares shaded, which is 25%

What your child learns in P5 percentage

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

Follows the latest (2026) MOE syllabus

See the syllabus wording

expressing a part of a whole as a percentage
use of %
finding a percentage part of a whole
finding discount, GST and annual interest

Percent means out of 100

The sign % means out of 100. One quarter, 0.25 and 25% are the same amount written three ways. A decimal becomes a percentage when you multiply it by 100.

25 out of 100 is 25%

A part of a whole as a percentage

Write the part over the whole, then make the denominator 100. $30 out of $50 is the same as 60 out of 100, so it is 60%.

$30 of $50 is 60%

A percentage of an amount

Find 10% or 1% first, then scale up. 10% of 240 is 24, so 30% of 240 is 72.

30% of 240 is 72

Discount, GST and annual interest

A discount is a percentage taken off the usual price. GST is a percentage added on. Annual interest is a percentage of the money in the bank, paid each year. Each is a percentage of the amount before the change.

25% off an $80 price

Key facts and formulas

Term 3

Percent means out of 100To a percentage, × 100%. Back to a decimal, ÷ 100. $45\% =$ $\frac{45}{100} =$ $0.45$ $0.08 \times 100\% =$ $8\%$
Part as a percentage $\frac{\text{part}}{\text{whole}} \times 100\%$ Example18 out of 24 → $\frac{18}{24} \times 100\% =$ $75\%$
Fractions as percentages $\frac{1}{4} =$ $25\%$ $\frac{1}{5} =$ $20\%$ $\frac{1}{8} =$ $12.5\%$
Percentage of a quantity15% of $60 → $\frac{15}{100} \times 60 =$ $\text{\textdollar}9$
DiscountPrice after discount = usual price − discount20% off $45 → $\frac{20}{100} \times 45 =$ $\text{\textdollar}9$ pay → $45 - 9 =$ $\text{\textdollar}36$
GSTPrice with GST = price + GST. Use the rate the question gives.9% GST on $200 → $\frac{9}{100} \times 200 =$ $\text{\textdollar}18$ pay → $200 + 18 =$ $\text{\textdollar}218$
Annual interestA percentage of the money saved, paid each year.3% a year on $2500 → $\frac{3}{100} \times 2500 =$ $\text{\textdollar}75$ after 1 year → $2500 + 75 =$ $\text{\textdollar}2575$

Words to know

Percent: Out of 100. The sign is %, so 30% means 30 out of 100.
Hundredths: The parts of a whole cut into 100 equal pieces. 0.3 is 30 hundredths.
Equivalent: Equal in value. One quarter, 0.25 and 25% are equivalent.

The sentence that costs the mark

Write 0.3 as a percentage.

What the working usually does

× 100.3=3%

Moves the decimal point one place. It lands on a clean percentage, so the working looks finished.

What the question asked

× 1000.3=30%

Moves the point two places, because a percentage is a count out of a hundred, not out of ten.

Both give a tidy percentage and 3% looks like a real figure, so nothing looks careless. The only check is what percent means: 0.3 is thirty hundredths, so it has to be 30%.

The same P5 percentage 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.

What is 0.8 written as a percentage?

Step 1 of 4▌

A percentage is a number out of 100. Draw a bar for 1 whole, which is 100%, and cut it into 10 equal units. 0.8 is 8 of them.
To change a decimal to a percentage, multiply it by 100: 0.8 × 100 = 80. Multiplying by 10 gives 8%, which is far too small.
Each unit is 10% of the whole, so the 8 units are 8 × 10% = 80%.
So 0.8 is 80%.

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

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Three quick P5 percentage questions

Try them together, then tap to check.

Question 1

Priya had $80. She spent $32 on a toy. What percentage of her money did she spend?

Show answer

Answer40%. She spent 32 out of 80, and $\frac{32}{80}$ = $\frac{40}{100}$ , which is 40 out of 100.

Question 2

A farmer collected 350 eggs. 20% of them were brown. How many brown eggs were there?

Show answer

Answer70. 10% of 350 is 35, so 20% is 2 × 35 = 70.

Question 3

A pair of shoes has a usual price of $120. Ramesh bought them at a 25% discount. How much did he pay?

Show answer

Answer$90. The discount is 25% of $120, which is $30, so he paid $120 − $30 = $90.

Helping at home

How to tell it has clicked

You can check this without doing the conversion yourself. Ask your child what percent means, in their own words. If the answer is out of a hundred, they have the one idea the question tests.

Then ask them to write 0.3 as a percentage and watch which way the point moves. Two places to 30% is right. One place to 3% is the slip, and it is the same slip every time.

Try this tonight

Money makes it concrete. A dollar is 100 cents, so cents are already counted out of a hundred. Thirty cents out of a dollar is 30%.

Ask what 0.3 of a dollar is in cents. Thirty, not three. The dollar being a hundred is what turns the decimal into the percentage.

Before and after P5 percentage

Builds on
Primary 4 Decimals
Compares decimals place by place
Builds on
Primary 5 Fractions and Division
Takes a fraction of what is left
You are here
Primary 5 Percentage
Writes parts of a whole out of 100
Head Start
How to prepare for PSLE Maths: P5 to P6 revision
One of five P5 topics to revise before P6 Term 1
Leads to
Primary 6 Percentage
Finds the whole and the percentage change

The methods your child will use here

More in Primary 5

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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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