A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The prefix "kilo-", for example, may be added to "gram" to indicate "multiplication" by one thousand: one kilogram is equal to one thousand grams. The prefix "milli-", likewise, may be added to "metre" to indicate "division" by one thousand; one millimetre is equal to one thousandth of a metre.