The decimetre (SI symbol dm) or decimeter (American spelling) is a unit of length in the metric system, equal to one tenth of a metre (the International System of Units base unit of length), ten centimetres or 3.937 inches.

The common non-SI metric unit of volume, the liter, is defined as one cubic decimeter (however, from 1901 to 1964, there was a slight difference between the two due to the liter being defined with respect to the kilogram rather than the meter).

The commonly used units of measurement are millimeter, centimeter, meter, and kilometer. A decimeter is not as widely used, but is an important unit. In real life, we rarely find measurements written in decimeter. Since one meter is not a very long length, it is easier to use 0.1 m or 0.5 m when the length is shorter than a meter.

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