Adding and subtracting fractions is easier than you might think. It can seem tricky when you first get started, but with some practice you’ll be flying through them in no time. You just need to remember the simple method set out below. Follow the step-by-step guide and do the practice questions. If you would like any further help at that stage, then you can contact us to talk things through with one of our expert maths tutors.
Adding fractions step 1:
To start with you need to make sure the denominators (numbers on the bottom) are the same on both fractions. Do this by finding the lowest common multiple of both denominators. For example with:
The lowest common multiple of 3 and 2 is 6.
Then multiply both denominators up to that number (if in doubt just multiply the denominators by each other). Make sure you then remember the golden rule of fractions – whatever you do to the denominator, you must also do to the numerator (the number on top). So you need to multiply the numerators by the same number as the denominator.
In the example of 1/3 + 1/2 you have multiplied the 3 by 2 to get to 6 and the 2 by 3 to get to 6, so you need to do the same to the numerators:
The final step is then simply to add or subtract across the numerators. So the final sum is:
Remember that the method is exactly the same for subtracting fractions. All you need to do differently is subtract the numerators at step 3.
Use what you have learnt here to have a go at the practice questions set out below.
Adding and subtracting fractions – practice questions
2/5 + 1/3
1/2 + 1/5
1/3 + 2/7
3/4 – 1/3
2/3 – 1/4
5/6 – 1/4