Perimeter (Year 4)
Calculate the perimeter of 2D shapes by adding side lengths.
The questions below are generated to match the National Curriculum for Year 4 and get harder as you progress from Rookie to Guru.
Worked examples
Read the time: 14:35. What time is this in 12-hour form?
- 2:35 PM
- 4:35 PM
- 1:35 PM
- 14:35 PM
Answer: 2:35 PM. After 12:00, subtract 12 to get the PM hour. 14 − 12 = 2 → 2:35 PM.
A jug holds 1.5 litres. How many millilitres is this?
- 1,500 ml
- 150 ml
- 15 ml
- 15,000 ml
Answer: 1,500 ml. 1 litre = 1,000 ml. 1.5 × 1,000 = 1,500 ml.
Why does the formula A = L × W give cm² as the unit (not cm)?
- Because we multiply length × length — each in cm — and cm × cm = cm² (square centimetres).
- Because the answer is bigger than length.
- Because two-digit numbers always have squared units.
- Because the question said so.
Answer: Because we multiply length × length — each in cm — and cm × cm = cm² (square centimetres).. Multiplying cm × cm gives cm² — square centimetres — because we're measuring area.
Related skills
Frequently asked questions
- What is perimeter?
- Calculate the perimeter of 2D shapes by adding side lengths.
- How can my child practise perimeter at home?
- Work through the examples below, then start a free adaptive session. Northstar adjusts the difficulty automatically and tracks mastery over time.
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