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Competencies covered

MSFGN2001: Make measurements and calculations

The metric system

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Before the 1970s, the units of measure used in Australia generally came from the imperial system.

This was a reference to 'imperial' Britain, because that's where the system was first developed.

Length, for example, was measured in inches, feet, yards and miles.

Weight was measured in ounces, pounds, stone and tons.

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However, between the 1970s and 1980s Australia progressively converted its measurement units across to the International System of Units - called the 'SI' (an abbreviation of the French 'Système International').

This is commonly referred to as the metric system.

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The metric system is based on the decimal system of numbers. This means that all measurement units are based on multiples of 10.

For example, the standard unit of length is the metre. So the other units used to denote longer and shorter lengths are in multiples of 10 from the 'one metre' standard. Click on the link below to see the table of metric length units ranging from the millimetre (mm) to the kilometre (km).

Table of metric lengths from mm to km

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As you look down this list of terms, you'll probably notice that not all of these units are commonly used.

Metres and kilometres are terms used by just about everyone, including in ordinary day-to-day conversations.

Millimetres are widely used in building, construction and manufacturing.

Centimetres are also common in particular fields.

But decimetres, decametres and hectometres have only limited usage in specialist areas.

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Nonetheless, the prefix (first half of the term) of each of these units is very handy to know, because it tells you what the quantity is in relation to the standard unit of measure, whatever it is that you're measuring.

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For example:
Milli always means 1/1000, so:

  • 1 millimetre (mm) is 1/1000 of 1 metre (m)

  • 1 millilitre (mL) is 1/1000 of 1 litre (L)

  • 1 milligram (mg) is 1/1000 of 1 gram (g)
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Kilo always means 1000, so:

  • 1 kilometre (km) is 1000 metres

  • 1 kilolitre (kL) is 1000 litres

  • 1 kilogram (kg) is 1000 grams.
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Learning activity

Audio 8 (mp3 |6|KB)

Below is a table showing various lengths in kilometres (km) centimetres (cm) and millimetres (mm). Rewrite each of these measurements in metres, or proportions of a metre by entering the correct answers in the right hand column.

Remember that the decimal point is critical in metric measurements. If you're not sure where the point should go, refer back to the table of metric lengths.

It's also good practice to put a zero in front of the decimal point if the number is less than 1. That is, it's better to write '0.5' than '.5', because there is less chance of misreading the measurement when you come back to it later.

When you've finished, click on the 'Check your answers' button to see how you went.

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Convert these measurements to metres valueUnit of measure
1.5 km1500m
1 km1000m
1/2 km500m
1/4 km250m
350 cm3.5m
185 cm1.85m
4800 mm4.8m
3660 mm3.66m
900 mm0.9m
255 mm0.255m
75 mm0.075m
25 mm0.025m
9 mm0.009m
3 mm0.003m

  Go to  Using tallies