Unit of measure of length equal to one-thousandth of a metre.

### Notations

- The symbol is “mm” which represents “millimetre.”
- One metre is equal to 1000 millimetres and we write: 1 m = 1000 mm.
- One millimetre is equal to one-thousandth of a metre and we write: 1 mm = 0.001 m.
- One millimetre is equal to on-hundredth of a decimetre and we write: 1 mm = 0.01 dm.
- One millimetre is equal to one-tenth of a centimetre and we write: 1 mm = 0.1 cm.