Solving Primary 4 Math Word Problems Using the Assumption Method
- AGrader Learning Centre
- 9 hours ago
- 5 min read
If you’ve ever seen your child struggle with Primary 4 maths word problems, you’re not alone. Word problems can be daunting — especially when they involve multiple steps or unfamiliar approaches. But there’s a powerful method that makes even tricky multi-step word problems simpler: the Assumption Method, also known as the Supposition Method.
This method is widely used in Primary 4 maths questions across Singapore and is perfect for teaching children how to solve word problems logically and confidently.
Let’s dive into what this method is all about, when to use it, and how it builds critical thinking skills while establishing a strong foundation in math concepts.
Table of Contents:
What Is the Assumption Method?
The Assumption Method helps solve math word problems when:
There are two types of items, each with a different value (like number of legs, wheels, or money). E.g. A car (item 1) has 4 wheels (value), while a bicycle (item 2) has 2 wheels (value).
The total value is given, but the exact quantity of each item is unknown.E.g. There are 56 wheels in total. There are 16 cars and bicycles together.
This method involves solving the problem by assuming all the items are of one type, then adjusting based on the difference in values. It’s especially handy for operations word problems involving addition, subtraction, multiplication and division.
Why Teach This to Primary 4 Students?
By Primary 4, students are ready to tackle more complex types of word problems. The Assumption Method:
Encourages logical thinking and step-by-step reasoning.
Reinforces understanding of math concepts like difference, total value, and comparison.
Teaches them how to solve word problems even when the answer isn’t immediately obvious.
Gives them a clear strategy for handling multi-step word problems.
Enhances critical thinking skills and mental flexibility.
In Singapore, Primary 4 maths word problems often feature these types of puzzles — making it vital for students to be comfortable with this approach.
Step-by-Step Guide: Assumption Method in Action
Let’s look at a classic example of a math problem that uses this technique:
Question: There were 14 rabbits and chicks in a zoo. There were 38 legs in total. How many chicks were there?
Step 1: Identify the total and individual values.
Total number of animals: 14
Total legs: 38
Rabbits have 4 legs. Chicks have 2 legs.
Step 2: Make an assumption.
Assume all 14 animals are rabbits.
Step 3: Calculate the total number of legs based on assumption.
14 × 4 = 56 legs
Step 4: Find the total difference.
56 (assumed total) − 38 (actual total) = 18
Step 5: Find the individual difference between values.
4 − 2 = 2 legs
Step 6: Divide to find number of chicks.
18 ÷ 2 = 9 chicks
Always check your answer if you have extra time.
Total legs for chicks → 9 × 2 = 18
Total legs for rabbits → 5 × 4 = 20
Total legs → 20 + 18 = 38
The answer is correct.
This structured approach helps children solve word problems confidently, even when they appear tricky at first.
More Practice Questions
Here are more examples of Primary 4 maths questions that can be solved using the Assumption Method:
1. Farm Animals
There are 62 cows and chickens. The total number of legs is 200. How many chickens are there?
Assume all are cows (4 legs each): 62 × 4 = 248 248 − 200 = 48 4 − 2 = 2 48 ÷ 2 = 24 chickens
2. Motorcycles and Cars
There were 50 motorcycles and cars. The total number of wheels was 180. How many cars were there?
Assume all are motorcycles (2 wheels each): 50 × 2 = 100 180 − 100 = 80 4 − 2 = 2 80 ÷ 2 = 40 cars
3. Goats and Ducks
There are 80 goats and ducks. The total number of legs is 248. How many goats?
Assume all are ducks (2 legs each): 80 × 2 = 160 248 − 160 = 88 4 − 2 = 2 88 ÷ 2 = 44 goats
4. Money Notes
Mr Ng had 70 notes, made up of $2 and $10 notes. The total value is $516. How many $10 notes?
Assume all are $2 notes: 70 × $2 = $140 $516 − $140 = $376 $10 − $2 = $8 $376 ÷ $8 = 47 ten-dollar notes
These are real-life scenarios that help children apply math word problems to practical thinking.
When Should You Use the Assumption Method with Primary Math Word Problems?
This method works especially well for:
Addition word problems with constraints.
Subtraction word problems that involve differences.
Division word problems where a total is broken down into types.
Word problems involving quantity and value differences.
Find the total type questions where totals are broken down by type.
In short, whenever you have two types of items with different values and need to work backwards from the total, this is the method to go for.
The Assumption Method is a fantastic tool to help students solve word problems confidently. By teaching them to look at a problem differently — to think, test, and revise — we equip them with more than maths skills. We give them confidence, resilience, and critical thinking skills that stretch far beyond the classroom.
So whether it's division word problems or mystery-legged animals at the zoo, encourage your child to give the Assumption Method a go. With enough practice, they’ll soon become experts at solving Primary 4 math word problems — one clever assumption at a time.
Enrolling your child in AGrader Learning Centre’s Primary Math Programme isn’t just another tuition option — it’s a strategic head start in mastering maths with confidence. Every weekly lesson is thoughtfully designed to stay ahead of the school syllabus, aligning precisely with the latest MOE curriculum to ensure relevance and depth. With engaging, in-house curated worksheets and dedicated teachers guiding the way, your child will be empowered not just to keep up, but to excel. And with complimentary access to the EverLoop Improvement System — including revision materials from up to three previous levels — students gain the advantage of consistent reinforcement and advanced problem-solving strategies that tackle even the toughest questions.
Don’t leave your child’s progress to chance — enrol at AGrader today and give them the confidence to conquer Primary Maths with ease!
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