**Units of length:** The basic unit of length measurements in metric units is a metre (m).

1 millimetre (mm) = \( \frac{1}{1000m} \scriptsize = 10^{-3}m\)

1 centimetre (cm) = \( \frac{1}{100m}\scriptsize = 10^{-2}m\)

1 decimetre (dm) = \( \frac{1}{10}\scriptsize = 10^{-1}m\)

1 decametre (Dm) = 10m = 10^{1}m

1 hectometre (Hm) = 100m = 10^{2}m

1 kilometre (Km) = 1,000m = 10^{3}m

### Length Measuring Tools:

1. **Scale rulers: **A ruler is either made of steel, plastic, or wood and is normally graduated in centimetres (cm). Each centimetre(cm) is sub-divided into ten divisions to give 0.1cm or each division of 1mm. Standard lengths of rulers are normally 30cm, 500cm, or 1.0m.

2. **Measuring Tapes:** Measuring tapes are usually used for measuring longer distances by tailors, bricklayers, carpenters, surveyors, etc. Measuring tapes are made of steel or cloth, graduated in centimetres, with or without sub-divisions in millimetres.

The length of the tapes varies and they include 60cm (tailorâ€™s measuring tape), 300cm (carpenterâ€™s measuring tape), and 5m to 50m (bricklayerâ€™s measuring tape). The graduated tapes are usually housed in steel or plastic cases when not in use.

### Measurements of Volume:

**Units of volume:** The basic unit of volume is litre (L). The cubic centimetre (c.c or cm3) and millimetre (ml) are also commonly used.

1 millimetre (ml) = 1c.c

1 centilitre (cl) = \( \frac{1}{10^2}\) litre = 10ml

1 litre (L) = 1000ml = 1000cc

Conversion units are:

1cm^{3} = 1c.c = 1ml = 10mm x 10mm x 10mm = 10^{3}mm^{3}

1m^{3 }= 100cm x 100cm x 100cm = 10^{6}cm^{3}

1m^{3} = 10dm x 10dm x 10dm = 10^{3}dm^{3}

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