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 number 2 diesel does a truck tanker hold? 7500 gallons due to the weight not the available volume in the  tank. How many liters are there in a tanker truck? A semi trailer in Australia can carry 40 000 litres of unleaded petrol and a B double carries 57 000 litres due to on road weight restrictions.