def terra(unit): """si prefix""" return core.factor_unit(1.e12, unit, name='terra' + unit.name, symbol='T' + unit.symbol)
def mega(unit): """si prefix""" return core.factor_unit(1.e6, unit, name='mega' + unit.name, symbol='M' + unit.symbol)
def giga(unit): """si prefix""" return core.factor_unit(1.e9, unit, name='giga' + unit.name, symbol='G' + unit.symbol)
def hecto(unit): """si prefix""" return core.factor_unit(100., unit, name='hecto' + unit.name, symbol='h' + unit.symbol)
def kilo(unit): """si prefix""" return core.factor_unit(1000., unit, name='kilo' + unit.name, symbol='k' + unit.symbol)
def zetta(unit): """si prefix""" return core.factor_unit(1.e21, unit, name='zetta' + unit.name, symbol='Z' + unit.symbol)
def centi(unit): """si prefix""" return core.factor_unit(0.01, unit, name='centi' + unit.name, symbol='c' + unit.symbol)
def atto(unit): """si prefix""" return core.factor_unit(1.e-18, unit, name='atto' + unit.name, symbol='a' + unit.symbol)
def zepto(unit): """si prefix""" return core.factor_unit(1.e-21, unit, name='zepto' + unit.name, symbol='z' + unit.symbol)
def pico(unit): """si prefix""" return core.factor_unit(1.e-12, unit, name='pico' + unit.name, symbol='p' + unit.symbol)
def femto(unit): """si prefix""" return core.factor_unit(1.e-15, unit, name='femto' + unit.name, symbol='f' + unit.symbol)
def nano(unit): """si prefix""" return core.factor_unit(1.e-9, unit, name='nano' + unit.name, symbol='n' + unit.symbol)
def micro(unit): """si prefix""" return core.factor_unit(1.e-6, unit, name='micro' + unit.name, symbol='mu' + unit.symbol)
def milli(unit): """si prefix""" return core.factor_unit(0.001, unit, name='milli' + unit.name, symbol='m' + unit.symbol)
def peta(unit): """si prefix""" return core.factor_unit(1.e15, unit, name='peta' + unit.name, symbol='P' + unit.symbol)
def yocto(unit): """si prefix""" return core.factor_unit(1.e-24, unit, name='yocto' + unit.name, symbol='y' + unit.symbol)
def exa(unit): """si prefix""" return core.factor_unit(1.e18, unit, name='exa' + unit.name, symbol='E' + unit.symbol)
def deca(unit): """si prefix""" return core.factor_unit(10., unit, name='deca' + unit.name, symbol='da' + unit.symbol)
def yotta(unit): """si prefix""" return core.factor_unit(1.e24, unit, name='yotta' + unit.name, symbol='Y' + unit.symbol)
def deci(unit): """si prefix""" return core.factor_unit(0.1, unit, name='deci' + unit.name, symbol='d' + unit.symbol)