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 are in 1 cup?   Gallons per cup   It is a bit stange to ask how many gallons -- plural -- are in a cup, because the gallon is a larger unit of measure than the cup. We usually thinâ¦k of cups per gallon. But no matter.   Since there are 16 cups per gallon, we can say there is one gallon per 16 cups.