Number that expresses a length. This number is related to the unit of measure used.
Conventional units of measure such as the millimetre and the centimetre are commonly used to measure line segments.
To measure the blue segment below, any of the 4 unconventional units of measure identified by the letters A to D can be used.
The blue segment measures 12 A units, 4 B units, 3 C units or 2 D units.