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 of water does a twenty gallon fish tank hold? a 20 GALLON tank does have a capacity of 20 gallons.   Hope you have a great time with your spacious (to me at least)  aquarium, i have a 5 gal. because that is all i canâ¦ support and  afford right now, for a 20 gal.