5 Need-To-Know Concepts For GCSE Maths

GCSE Maths Key Concepts

As any teacher will tell you,  if your knowledge of the basic topics in Maths GCSE is not 100% secure, then no amount of GCSE past papers are going to help you revise! 

Whether you are approaching your first ever set of GCSE Mock Exams or if you’re nearing the real exam date, it’s always a good time to refresh your understanding of the essential concepts. It will help you to boost your confidence AND your grades!

We’ve asked our Maths exam experts to put their heads together and produce these clear, short explanations. And of course, if you want to more in-depth explanations for any of the topics, head straight over to our complete collection of Revision Notes.

Now here’s a run-down of some key Maths concepts that will help you soar in lessons this year:

1. How to find the equation of a straight line

This is a topic almost guaranteed to come up in any GCSE Maths exam. Once you’ve gotten the hang of it, it couldn’t be easier!

The general equation of a straight line is y = mx + c, where:

  • m is the gradient (how steep the line is). The bigger the number, the steeper it is. If it’s negative the line will go down, not up.
  • c is the y-intercept (where the line crosses the y-axis). This point has coordinates (0, c)

If you know the coordinates of two points on the line (x and y) you can work out the equation of that line. 

2. Statistics

You’d be surprised at the number of GCSE students who still get confused when it comes to calculating the mean, mode, and median of a data set.


  • The median is the middle value when the data is arranged from smallest to largest (if there are two middle values, the median is halfway between these values) 
  • You can calculate the mean by adding together all of the values in the data set and dividing them by the number of items in the set 
  • The mode is the value which appears most frequently in the data set

For more on this topic, including how to calculate range and interquartile range, check out this revision video!

3. Geometry: Key Formulae

This is no time for excuses! Learn these formulae and you’ll be over the first hurdle when it comes to answering geometry questions with confidence. 

Once you’ve committed these formulae to memory, build on your knowledge by checking out our ‘Geometry and Measures’ revision videos.

4. Mastering percentage increase and decrease

To successfully increase and decrease a value by a percentage, it’s important to understand that you always start with 100%.

If you want to find out what 85% of that value is, you’ll multiply the original value by 0.85. If you want to find out what 63% of a value is, you’ll multiple the original value by 0.63. Get the gist?

Finding 85% is the SAME as reducing the original value by 15%. Finding 63% is the same as reducing the original value by 37%.

5. Your calculator can be your best friend in Maths lessons (IF you know how to use it properly)

Despite the incredible computing power of a typical calculator, it can be difficult to use it correctly. With so many settings and functions available, simple mistakes can lead to a whole host of problems with your calculations!

Make sure you’ve read your calculator instruction manual or, even better, watched the instruction videos on the manufacturer’s website before using your calculator.

We have also created step-by-step video guides to help you use your calculator effectively and make the most out of this brilliant tool. 

Once you’ve understood the techniques, test your skills with some past paper calculator Topic Questions. Check out our video solutions as you mark your work, to ensure you’re using the right methods to get to your answer, and spot where you might be going wrong.

Now you’ve mastered these basics, are you ready to  take your revision to the next level? 

Edexcel GCSE Revision Notes

AQA GCSE Revision Notes 

OCR GCSE Revision Notes

CIE IGCSE Revision Notes 

Edexcel IGCSE Revision Notes