Math Tip for P5: Mastering the Excess and Shortage Method
- AGrader Learning Centre
- Jul 14
- 5 min read
It’s a common scenario in many homes and classrooms: a Primary 5 (P5) student is tackling a problem sum and gets stuck on one that mentions "if," "leftover," or "needs more." Cue the frustration. Parents lean over to help but find the question confusing too. Sound familiar?
At this stage in primary 5 math, students are expected to solve increasingly complex word problems that require more than just basic operations. One method that often trips students up—but is essential to master—is the excess and shortage method.
This method appears in many tricky problem sums, and once mastered, it can significantly boost a student's confidence and accuracy. If your child is struggling to grasp this concept, or you as a parent are finding it difficult to explain it, this article will walk you through it clearly—with visuals, examples, and tips to help your child master the excess shortage method with ease.
Table of Contents:
What Is the Excess and Shortage Method in P5 Math?
The excess and shortage method is a powerful tool in P5 Math used to solve problem sums involving two different outcomes based on the same group of items being shared differently.
This method is typically used when:
The difference between two scenarios is known.
The total quantity involved stays the same.
The quantities change by the same amount per individual.
How Do You Know When to Use the Excess Shortage Method?
Look out for the following clues in problem sums:
Words like “If” or “When”
Mention of “excess” or “shortage”
Phrases like “left over,” “need more,” or “not enough”
These clues signal that the shortage method (or its counterpart, the excess method) is applicable.
Step-by-Step Guide to the Excess and Shortage Method
Let’s break down how to tackle these problems in three simple steps:
Step 1: Use Bar Models to Visualise
Drawing helps! Use bar models to represent the two different scenarios. Dotted lines can indicate a shortage, and bold or extra parts can show excess.
Step 2: Calculate the Differences
Add the total excess and shortage together. Then, divide by the difference in quantity per person/item to find out how many people (or items) are involved.
Step 3: Solve and Check
Once you find the number of people or items, calculate the total quantity. Always do a quick check to confirm your answer makes sense.
Example 1:
A group of boys share a packet of erasers among them.
If each boy is to get 7 erasers, they will need 6 more erasers.
If each boy is to get 4 erasers, there will be 3 erasers left.
How many erasers are there in the packet?
Step 1 : Draw simple bar models to visualise the excess or shortage.
1. Label the “shortage” with dotted lines.
2. Label the “excess” in the model (within the model with bold lines).
Step 2: Find the individual and total difference.
Total difference: 6 + 3 = 9
Individual difference between the number of erasers each boy takes: 7 − 4 = 3
Number of boys: 9 3 = 3
Number of erasers: 7 × 3 = 21
21 − 6 = 15
There are 15 erasers in the packet.
Step 3: Check your answer!
Tip: You can always check your answer in excess and shortage method!
Check
15 + 6 = 21
21 ÷ 7 = 3
Try yourself!
Example 2:
Mrs. Lim wanted to give each of her students an equal number of bonus bucks. If she gives each student 5 bonus bucks, she will have 2 bonus bucks left over. If she gives each student 8 bonus bucks, she will need another 10 bonus bucks. How many bonus bucks does she have?
10 + 2 = 12
5 – 2 = 3
12 ÷ 3 = 4 (number of students)
4 × 5 = 20
20 + 2 = 22
She has 22 bonus bucks.
Why Is the Excess and Shortage Method Important in Primary 5 Math?
At the Primary 5 Math level, students transition from simple arithmetic to more advanced problem-solving. The excess and shortage method encourages:
Logical thinking: It requires comparison and deduction.
Bar model drawing: A visual approach that strengthens understanding.
Real-world application: Sharing, allocation, and distribution problems are common in daily life.
It’s also a method frequently tested in exams because it assesses a student’s ability to interpret and analyse word problems logically.
Tips for Helping Your Child Master This Method
1. Encourage Drawing
Even if your child thinks it’s unnecessary, drawing bar models is a proven method for boosting comprehension.
2. Practise Identifying Clues
Make a game out of spotting words like “if,” “left,” “need more,” or “extra.” These are gold clues for the shortage method or excess shortage method.
3. Reinforce Through Practice
Try mixing up similar problems with changed numbers. This builds fluency and confidence.
4. Check with Backwards Calculation
After solving, always encourage your child to plug the answer back into the original question to verify it works.
5. Use Real-Life Examples
Turn daily scenarios—like sharing snacks or allocating chores—into fun math problems to reinforce the concept.
By helping your child master the excess and shortage method, you're not just prepping them for an exam—you're teaching them how to think logically, work systematically, and build resilience through problem-solving.
Primary 5 is a crucial year in your child’s academic journey. It’s the year where concepts get tougher, problem sums become more complex, and students are expected to apply multiple strategies in one question. More importantly, it sets the foundation for the PSLE in Primary 6.
At AGrader Tuition Centre, we understand how important it is to build solid fundamentals at this stage. Our Primary Math Programme is specially designed to help students grasp new topics confidently, stay ahead of their school curriculum, and avoid the stress of last-minute catching up in Primary 6.
Every lesson at AGrader is thoughtfully designed and taught ahead of the latest MOE syllabus. This means your child gets early exposure to upcoming topics, which helps them build understanding and confidence before they encounter the same material in school.
To support this learning, we provide specially curated worksheets created by our experienced academic team. And that’s not all. Every student at AGrader receives free access to our unique EverLoop Improvement System. This system empowers your child to revise and master topics from up to three previous academic levels. It’s a powerful way to fill in learning gaps, reinforce foundational knowledge, and give your child the confidence to handle even the toughest PSLE Math questions.
With no hidden fees and a strong emphasis on steady, meaningful progress, AGrader offers your child the support they need to approach Primary 5 with confidence and grow into a PSLE-ready student.
Start early, stay strong. Enrol your child in AGrader’s Primary 5 Math Programme today—and give them the head start they need for Primary 6 and beyond.
Join Our AGrader Community Today! (Free for all AGrader & Non-AGrader students)
Join our Telegram and WhatsApp channels to gain access to more study tips, free downloads, and much more for all subjects.
- WhatsApp channel: https://bit.ly/agwachannel
- Telegram channel: https://bit.ly/agtelchannel
Feel free to explore more related topics in this section:
Walkthrough of PSLE Maths 2024 Questions with Sample Solutions
6 Key Strategies for PSLE: Preparing Your Child for P6 Maths
Mastering the 4 Most Common Pattern Questions in PSLE and Primary Math
Most Common Mistakes Students Make in PSLE Math Circle Questions
PSLE Math's Area and Perimeter Questions and Summary of Formulas You Need to Know
Exploring Angles Concepts and Properties for Primary 5 & PSLE Math
Comments