Subtracting Fractions
Common denominator, then subtract numerators.
Key idea
Common denominator, then subtract numerators.
In depth
Same idea as addition: a common denominator first, then subtract numerators. Check the sign when the second fraction is larger.
Worked example
3/4 − 1/6 = 9/12 − 2/12 = 7/12.
Formula
Real-world uses
- Working out how much of a fuel tank or a book remains
- Calculating leftover material
Common mistake
Subtracting numerators and denominators separately.
How to learn this
- Read the key idea and say it in your own words.
- Work through the worked example, then try a similar problem.
- Use the interactive lesson’s visual and mini-quiz to check the pattern.
Frequently asked questions
What is Subtracting Fractions?
Common denominator, then subtract numerators. It is a topic at the intermediate level in Arithmetic & Number Sense.
What is the formula for Subtracting Fractions?
The key formula is a/b − c/d = (ad − bc)/bd.
Where is Subtracting Fractions used in real life?
Real-world examples: Working out how much of a fuel tank or a book remains; Calculating leftover material.
What should I learn before Subtracting Fractions?
Make sure you are comfortable with Adding Fractions, the previous topic in Arithmetic & Number Sense.
What is a common mistake with Subtracting Fractions?
Subtracting numerators and denominators separately.
How can I practise Subtracting Fractions?
Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.
What comes after Subtracting Fractions?
Move on to Multiplying Fractions next.
Related intermediate topics in Arithmetic & Number Sense
- Long Multiplication – Multiply by each digit of the multiplier, shift by place value, then add partial products.
- Long Division – Divide, multiply, subtract and bring down repeatedly to get the quotient.
- Factors and Multiples – Factors divide a number exactly; multiples are its products with whole numbers.
- Divisibility Rules – Quick tests: by 2 last digit even, by 3 digit-sum divisible by 3, by 5 ends 0/5, by 9 digit-sum divisible by 9.
- Prime Numbers – A prime has exactly two positive divisors: 1 and itself.
- Composite Numbers – Numbers greater than 1 with more than two factors.