Using standard units
Length, time and volume are all examples of A property that can exist as a magnitude, usually with a numerical value. For example, speed (quantity) is measured in metres per second. that can be measured.
A unit of measurement is one unit of a quantity, for example, one second.
Standard units of measurement are the units most typically used to measure a quantity.
Units of length
Kilometres (km) and miles are the standard units used to measure long distances.
Smaller lengths are measured in metres (m), centimetres (cm) or millimetres (mm).
The distance from London to Manchester is approximately 264 km or 164 miles.
The battery in the picture is 2.6 cm or 26 mm wide.