The classic way to convey the error that exists in a measurement is a formula that shows the obtained measurement (X) as a sum of a true score plus some error. One version of this formula is: X = T + e. With this formula in mind, obtaining more precise measures depends on reducing error.
  Mega is the prefix meaning one million, therefore there are one million (1,000,000) gallons in a mega gallon.
How many gallons liquid US of volume and capacity system are in 1 beer barrel US? The answer is: The change of 1 bl (beer barrel US) unit for a volume and capacity measure equals = into 31.00 gal (gallon liquid US) as per its equivalent volume and capacity unit type measure often used.