Metric units go up in steps of 10, 100 or 1000 — not always 10. Changing a larger unit into a smaller one makes the number bigger, so you multiply by the fact for those units: 1 metre = 100 centimetres, 1 kilometre = 1000 metres, 1 kilogram = 1000 grams, 1 litre = 1000 millilitres. So 3 metres = 3 × 100 = 300 centimetres. Ask first whether the number should get bigger or smaller, then use the exact fact for the two units.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- metre
- a unit of length equal to 100 centimetres
- kilometre
- a unit of length equal to 1000 metres
- litre
- a unit of volume equal to 1000 millilitres
Worked examples
3 metres to centimetres
- 1.1 metre = 100 cm.
- 2.3 × 100 = 300 cm.
= 300
5 kilometres to metres
- 1.1 kilometre = 1000 m.
- 2.5 × 1000 = 5000 m.
= 5000
4 litres to millilitres
- 1.1 litre = 1000 mL.
- 2.4 × 1000 = 4000 mL.
= 4000
For parents
Method: Learn the key facts, then multiply.
What to say: Ask 'will the number get bigger or smaller?' A smaller unit needs more of them, so multiply.
Common mistakes:
- Multiplying by 10 for every step instead of 100 or 1000.
- Dividing instead of multiplying when going to a smaller unit.