Before measuring something, you need to know what unit to use. You can do this by estimating its approximate size. For measures such as speed you will use a formula.

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The table shows some of the most common units and their equivalents. Make sure you know these conversions.

Converting measurements | |||
---|---|---|---|

Length | \[{1}~{km} = {1,000}~{m}\] | \[{1}~{m} = {100}~{cm}\] | \[{1}~{cm} = {10}~{mm}\] |

Weight | \[{1~tonne} = {1,000}~{kg}\] | \[{1}~{kg} = {1,000}~{g}\] | \[{1}~{g} = {1,000}~{mg}\] |

Capacity | \[{1}~{l} = {100}~{cl}\] | \[{1}~{cl} = {10}~{ml}\] | \[{1}~{l} = {1,000}~{ml}\] |

To convert a larger unit to a smaller unit (eg \({m}\) to \({cm}\)), first check the number of smaller units needed to make \({1}\) larger unit. Then, multiply that number by the number of larger units.

To convert a smaller unit to a larger unit (eg \({cm}\) to \({m}\)), divide it by the number of smaller units which are needed to make \({1}\) larger unit.

To convert from a larger unit to a smaller one, multiply. To convert from a smaller unit to a larger one, divide.

\[1~m = 100~cm\]

So, to convert from \({m}\) to \({cm}\) multiply by \(100\), and to convert from \({cm}\) to \({m}\) divide by \(100\).

For example:

\[3.2~m = 320~cm~(3.2 \times 100 = 320)\]

\[400~cm = 4~m~(400 \div 100 = 4)\]

- Question
Convert the following to the units given in brackets:

a) \(5,120~g~(kg)\)

b) \(15~cl~(ml)\)

c) \(245~mm~(m)\)

a) \(5.12~kg\)

Remember that \(1~kg = 1,000~g\).

To convert from \({g}\) to \({kg}\), divide by \(1,000\).

b) \(150~ml\)

Remember that \(1~cl = 10~ml\).

To convert from \({cl}\) to \({ml}\), multiply by \(10\).

c) \(0.245~m\)

Remember that \(1~m = 1,000~mm\).

To convert from \({mm}\) to \({m}\), divide by \(1,000\).