Fractions with different denominators: a parent's guide
21 October 2026
Adding fractions with different denominators
Adding or comparing fractions with different denominators can feel tricky at first. For 11+ maths, this is a key skill that helps children handle more complex calculations with confidence.
Why different denominators matter
Fractions with different denominators cannot be added or compared directly. The denominators must be the same so that both fractions are split into equal parts. This is why we need to find a common denominator before working with them.
Step-by-step: how to add fractions with different denominators
1. Find the lowest common multiple (LCM) of the denominators.
2. Adjust each fraction so both have the same denominator. Multiply the numerator and denominator of each fraction as needed.
3. Add the numerators together. Keep the denominator the same.
4. Simplify the answer if possible.
Worked example
Add 2/3 + 1/4
1. The denominators are 3 and 4. The lowest common multiple of 3 and 4 is 12.
2. Convert each fraction: 2/3 = (2 × 4)/(3 × 4) = 8/12 1/4 = (1 × 3)/(4 × 3) = 3/12
3. Add the numerators: 8/12 + 3/12 = 11/12
4. 11/12 cannot be simplified further.
The answer is 11/12.
Practice makes perfect
Encourage your child to practise adding and comparing fractions with different denominators. Regular practice builds confidence and helps them spot patterns quickly. For extra support, explore the different denominator fractions package for targeted worksheets and step-by-step guidance.
Key insight: Mastering fractions with different denominators is essential for 11+ maths success, especially when adding or comparing fractions in more challenging problems.
