Adding Fractions
Convert to a common denominator then add numerators.
Key idea
Convert to a common denominator then add numerators.
In depth
You can only add pieces of the same size, so you need a common denominator. Convert, add numerators, keep the denominator, then simplify.
Worked example
1/4 + 1/6: LCD 12, so 3/12 + 2/12 = 5/12.
Formula
Real-world uses
- Combining ingredients measured in different units
- Totalling parts of a project completed in stages
Common mistake
Adding the denominators: 1/4 + 1/6 is not 2/10.
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 Adding Fractions?
Convert to a common denominator then add numerators. It is a topic at the intermediate level in Arithmetic & Number Sense.
What is the formula for Adding Fractions?
The key formula is a/b + c/d = (ad + bc)/bd.
Where is Adding Fractions used in real life?
Real-world examples: Combining ingredients measured in different units; Totalling parts of a project completed in stages.
What should I learn before Adding Fractions?
Make sure you are comfortable with Comparing Fractions, the previous topic in Arithmetic & Number Sense.
What is a common mistake with Adding Fractions?
Adding the denominators: 1/4 + 1/6 is not 2/10.
How can I practise Adding 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 Adding Fractions?
Move on to Subtracting 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.