PSLE Mathematics: Percentage Mistakes That Cost Marks

Quick answer

Have you ever seen a percentage question in your PSLE paper and felt your heart sink? You thought you knew it, but the marks say otherwise. In this guide, I'll show you the common mistakes students make in percentage questions and how to avoid them, so you can keep those precious marks.

“Stuck on a question? See simple explanations that help you understand fast.”
👉 Give it a try and turn confusion into clarity in minutes.

What you need to know

Percentage is a way to express a number as a part of 100. It helps us understand proportions easily. For example, 50% means 50 out of 100. It's a common topic in PSLE Math, but it can trip students up if they're not careful.

“Access more than 1000+ past year papers to practice”
👉 Start a paper today and test yourself like it’s the real exam.

Common mistakes students make

Misreading the question

Often, students lose marks because they rush and misread the question. For example, if a question asks for "percentage increase," some students might calculate the percentage of the new amount instead.

Calculation errors

Sometimes, students make simple calculation mistakes, like adding instead of subtracting. Double-check your work to avoid this.

Forgetting to convert fractions or decimals to percentages

A simple trick I teach my students is to always convert fractions or decimals into percentages when asked. This part trips everyone up, but with practice, it becomes second nature.

Not simplifying answers

Sometimes, students forget to simplify their answers to the simplest form. Remember to always check if your percentage can be simplified further.

Ignoring units

In percentage questions, units matter. If the question is in dollars, your answer should be in dollars. Don't lose marks over something so simple!

Exam tip

Always underline key words in the question, like "increase," "decrease," or "of." This helps you focus on what the question is really asking. Also, allocate a few minutes at the end of the exam to review your calculations.

Worked examples

Question

A shirt costs $80. During a sale, the price is reduced by 20%. What is the sale price?

Solution

Step 1: Calculate the percentage decrease in dollars.
$80 \times \frac{20}{100} = 16$
Why: We find 20% of $80 to know how much the price is reduced by.

Step 2: Subtract the decrease from the original price.
80 - 16 = 64
Why: Subtracting the discount from the original price gives the sale price.

Quick check

1. What is 25% of $200?
2. A bag costs $120 and is sold at a 15% discount. What is the sale price?
3. If 40% of a number is 32, what is the original number?

“Doing Secondary Science? Pick a topic and practise like it’s a real exam — with clear answers right after.”
👉 Try Tutorly now and start a Science topic in seconds.


Quick summary

• Read the question carefully, underline key words.
• Convert fractions and decimals to percentages.
• Simplify your answers.
• Double-check your calculations.
• Be mindful of units in your answers.

FAQ

Q: How do I calculate percentage increase?
A: Find the difference between the new and old values, divide by the old value, then multiply by 100.

Q: What if I forget a formula during the exam?
A: Try to understand the concept behind the formula. This way, you can recreate it by thinking about the steps.

Q: How can I avoid careless mistakes?
A: Practice short daily sessions and review your work to catch errors early.

Q: Why do I need to simplify my answers?
A: Simplifying ensures your answer is in the simplest form, which is often required in exams.

Practise with free question sets

Work through exam-style questions with answers and step-by-step solutions:

• [35+ P 6 PSLE Percentage Questions for 2026/2027 (Singapore MOE Syllabus) with Answers and Explanations](/questions/p 6-percentage-questions)
• Topic study hub

[Practise unlimited questions on Tutorly.sg/app](https://www.tutorly.sg/app)

Related Topics You Should Learn Next

• PSLE Mathematics: Mastering Percentage with Simple Steps
• How to Solve PSLE Math Word Problems: Step-by-Step Guide (2026)
• Common PSLE Math Question Types In Singapore (With Strategies & Practice)
• PSLE Mathematics: Mastering Percentages with Confidence

“Practice PSLE Science questions and get clear, step-by-step answers instantly.”
👉 Try a question now and see how fast you can improve.