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.
1 Gallon [Fluid, US] = 231 Cubic Inches. 1 Gallon [Dry, US] = 268.802501 Cubic Inches. 1 Gallon [UK] = 277.419432 Cubic Inches. Gallon is an imperial and us customary unit. There is one type of gallon in imperial system and 2 types (liquid and dry) in united states customary system. It is widely used in daily life, such as measuring the fuel efficiency as miles per gallon, etc. The abbreviation is gal.