### Video Transcript

If five drops of water fill up a
volume of five milliliters, then how many drops would fill up a volume of seven
liters?

We’re told in the question that
five drops of water are equal to five milliliters. This means that one drop would be
equal to one milliliter. We need to calculate the number of
drops in seven liters. The prefix milli- means
one-thousandth. So a milliliter is one-thousandth
of a liter. We can therefore use the
calculation that 1000 milliliters is equal to one liter. Multiplying both sides of this by
seven gives us 7000 milliliters is equal to seven liters. We can therefore conclude that as
five drops of water filled up a volume of five milliliters, 7000 drops of water will
fill up a volume of seven liters.