Converting between units of measurement
Measured quantities are frequently used in calculations. Each of these quantities has a basic unit.
Three examples are:
 Mass..................basic unit gram (the S.I. base unit for mass is kilogram)
 Liquid volume.......basic unit litre
 Time .................basic unit second
Quantities are measured in the basic unit and multiples of the basic unit, such as microgram or millilitre. 'Micro' and 'milli' are prefixes that represent a conversion factor from the basic unit.
Commonly used prefixes
Prefix (symbol) 
Conversion from basic unit 
Example 
Mega (M) 
multiply by 1 000 000 (x 10^{6}) 
1.5 megaunits (Mu) =1.5 x 10^{6} =1 500 000 units 
Kilo (k) 
multiply by 1000 (x 10^{3}) 
2.25 kilogram (kg) = 2.25 x 1000 ^{} = 2250 gram (g) 
Basic unit 
no conversion needed (x10^{o}) 
7.5 gram (g) 
milli (m) 
divide by 1000 (÷ 10^{3}) 
15 millilitre (mL) = 15 ÷ 1000^{} = 0.015 litre (L) 
micro (µ) 
divide by 1 000 000 (÷ 10^{6}) 
55 microgram = 55 ÷ 10^{6} = 0.000 055
gram (g) 
Each unit differs from the one immediately above or below by a factor of 1000.
 When converting larger units to smaller units, multiply . You will have more smaller units than larger units.
 When converting smaller units to larger units, divide . You will have fewer larger units than smaller units.
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Converting between units  mass
