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 barrels in a gallon? Gallons to fluid barrels (bbl) volume conversion table shows the most common values for the quick reference. Alternatively, you may use the converter below to convert any other values. 1 Gallon [Fluid] = 0.0317460317 Barrel [Fluid] 1 Gallon [Fluid] = 0.0238095238 Barrel [Oil]