Units of length
We measure length in millimetres (mm), centimetres (cm) and metres (m). Use mm for tiny things, cm for a pencil, and m for a door or a room.
Key idea
1 cm = 10 mm · 1 m = 100 cm
Changing units
To change metres into centimetres, multiply by 100. To change centimetres into metres, divide by 100.
Worked example
How many centimetres are there in 2 m?
1 m = 100 cm, so 2 m = 2 × 100 = 200 cm.
Remember
- Bigger unit → smaller unit: multiply.
- Smaller unit → bigger unit: divide.
- 1 m 50 cm means 100 cm + 50 cm = 150 cm.