Perimeter calculation practice for 11+ Maths: GL & CEM style
20 October 2026
Understanding perimeter
Perimeter is an important topic for the 11+ maths exam. It often appears in GL and CEM style questions. Knowing how to find the perimeter helps children solve geometry problems with confidence.
What is perimeter
The perimeter of a shape is the total length around its outside. To find it, add up the lengths of all the sides.
How to find the perimeter of a rectangle
A rectangle has two pairs of equal sides. The opposite sides are always the same length.
Worked example
Let's use a rectangle that is 5 cm long and 4 cm wide.
First, write down all the sides: 5 cm, 4 cm, 5 cm, 4 cm
Add the two lengths: 5 cm + 5 cm = 10 cm
Add the two widths: 4 cm + 4 cm = 8 cm
Add both results together: 10 cm + 8 cm = 18 cm
The perimeter is 18 cm.
Practise together
Try measuring and adding the sides of different rectangles and other shapes with your child. Use real objects or draw shapes to make it hands-on. This builds confidence for perimeter questions in the 11+ exam.
Key insight: Clear step-by-step explanations and real examples make it easier for children to understand and apply perimeter in 11+ exams.
