Add & Subtract Lengths
Maths: Year 3 & 4 National Curriculum, topic 2.1.3
Adding and Subtracting Lengths
It is often useful to add and subtract lengths with the same unit or different units.
Same units
- To add lengths with the same unit, use your normal addition or subtraction method.
- Do not forget to write in the correct unit of measurement in your answer.
- 16 cm + 30 cm = 46 cm.
- 28 m - 7 m = 21 m.
Different units
- If the units of measurement are different, change them so they are the same (convert them).
- For example, 30 mm + 2 cm = ?
- 30 mm = 3 cm
- 2 cm = 20 mm
- 3 cm + 2 cm = 5 cm or 30 mm + 20 mm = 50 mm
Test yourself on Add & Subtract Lengths
What is 5 cm + 6 cm?
What is 32 m - 18 m?
What is 49 mm + 15 mm?