Convert from milligram to arroba [Portugal]

Unit Definition (milligram)
The milligram is a very common metric unit of mass equal to 0.001 gram or 1000 micrograms (µg or mcg). One milligram equals approximately 0.015432 grain or 35.274 x 10E-6 ounce.

Unit Definition (arroba [Portugal])
The arroba [Portugal] is a traditional unit of weight in Spain and Portugal, equal to 1/4 quintal. However, the Spanish and Portuguese quintals are of different sizes. In Portugal and Brazil, the arroba traditionally equals 32.38 pounds (14.69 kilograms, but in recent years this has been "metrized" to be exactly 15 kilograms). The arroba has also been used as a metric unit equal to exactly 15 kilograms. The name of the unit comes from ar rub', Arabic for "the quarter."