error

Sign: ±

This is the term for the difference between a value which is measured or counted, and its actual value.

This means that a measurement expressed to a specific unit has a possible error of half that unit.

For example, a piece of wood measures 28 cm, correct to the nearest centimetre. The actual length of the piece of wood can have a value between 27.5 cm and 28.5 cm. Therefore, the error is plus or minus 0.5 cm which is shown as ±0.5cm.