## Length

The basic unit for length in the metric system of measurement is the metre (m).

For measuring the lengths of short distances and objects, rulers can be used, using suitable units from the table below.

The commonly used units are millimetres, centimetres, metres and kilometres.

 Unit Symbol Examples millimetres mm Green peas are about 5 mm wide. centimetres cm A pen is about 12 cm long. metres m Most cars are about 3 to 5 metres long. kilometres km Distance from London in England to Paris in France is 279 km.

### Converting between Units

To convert between the units shown in bold in the first column and the units in the second column, multiply or divide by the factors indicated in the third column.

 Unit Convert to Action millimetres (mm) cm ÷ 10 m ÷ 1000 km ÷ 1 000 000 centimetres (cm) mm × 10 m ÷ 100 km ÷ 100 000 metres (m) mm × 1000 cm × 100 km ÷ 1000 kilometres (km) mm × 1 000 000 cm × 100 000 m × 1000

Examples

1. To change 8 cm into mm − multiply by 10.

8 cm = 8 × 10 mm = 80 mm

2. To change 500 m into km − divide by 1000

500 m = 500 ÷ 1000 km = 0.5 km