Using known area, perimeter, or volume to work backwards and find a missing length, width, or height.
Where your child meets this in real life: Determining the width of a room given the floor area and length, or height of a box given volume
Each SEAG paper has 28 maths questions. Questions 29 to 50 are multiple choice with five possible answers, and questions 51 to 56 need a short written answer. With 56 questions in 60 minutes across English and maths, that is about a minute per question.
SEAGReady breaks find missing dimensions into 3 steps, taught in order so each skill builds on the last.
Find a missing side of a rectangle when given the area and one side length
Find a missing side of a rectangle when given the perimeter and one side length
Find a missing dimension of a cuboid when given the volume and two other dimensions
Try three free questions from our find missing dimensions course. They start easy and get harder, so you can see where your child's confidence runs out. If they manage the last one without a hint, this topic is probably secure. If not, the steps above show where to start.
Use the diagram to find the missing width.
Use the diagram to find the missing side length.
The two identical crates shown have a total volume of 240 cm³. What is the height of each crate?
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Ava is buying a rug for her bedroom. The rug has an area of 24 m² and is 6 m long.
What is the width of the rug?
24 ÷ 6 = ?
Area = length x width
Step 1 of 4
Ava is buying a rug for her bedroom. The rug has an area of 24 m² and is 6 m long.
What is the width of the rug?
The rug is 4 m wide.
The key insight: Division is the opposite of multiplication - use it to work backwards!
Common mix-up: 24 x 6 = 144 m. Multiplying makes the number bigger, but we need to find a smaller piece of the area.
These are the misconceptions we see most often in find missing dimensions, including the ones our practice questions are specifically designed to catch.
Struggling with find missing dimensions? The real gap is often in one of these earlier topics.
Sitting the SEAG test this November? Read our last-month revision plan, Paper 1 vs Paper 2 and test day guide.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.
Free to start · no card needed