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Conversions between different-sized metric units may be needed to give the appropriate units for a measurement or calculation. 

Converting between metric units, and using the appropriate prefixes in the metric system (e.g. kilo–, mega–, centi–, milli–, micro–). The metric prefixes ‘kilo–’, ‘mega–’, ‘giga–’, and ‘tera–’ signify a unit that is one thousand, one million, one billion, and one trillion times larger than the base unit. 

The metric prefixes ‘centi–’, ‘milli–’, ‘micro–’, and ‘nano–’ signify a unit one hundredth, one thousandth, one millionth, and one billionth the size of the base unit.