Definition
Unit
A unit is the reference amount named beside a number in a measurement, such as metres, seconds, or litres.
What it means
The number tells how many measuring amounts there are. The unit tells which measuring amount is being used. In 2.4 litres, 2.4 is the number and litres is the unit. For a length, time, mass, or capacity measurement, the unit completes what the number means.
Remember it
Number + unit names a measured amount: how many, and how big each measuring step is.
Example
A ribbon is 1.5 metres long. The same ribbon is 150 centimetres long. The number changes because centimetres are smaller units, but the ribbon’s length does not change.
Watch for
Here, unit means a measurement reference. A school unit, apartment unit, military unit, or software unit test is a different sense of the word.
Common mix-up
Length is the quantity being measured; metre is a unit used to state that length.
Exact meaning
A unit is a chosen reference amount used to state or compare a quantity. A measurement pairs a number with a unit; when the same quantity is written in a different unit, the number can change while the quantity stays the same.