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.
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.
\[1~m = 100~cm\]
So, to convert from \({m}\) to \({cm}\) multiply by \(100\), and to convert from \({cm}\) to \({m}\) divide by \(100\).
For example:
\[3.2~m = 320~cm~(3.2 \times 100 = 320)\]
\[400~cm = 4~m~(400 \div 100 = 4)\]
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 \(1,000\).