### Video Transcript

Write the answer in milliliters:
3.15 liters plus 6250 milliliters.

When we see a question like this,
it can be tempting to rush in and start the addition straight away. However, we should notice that we
have two quantities that are given in different units. One is in liters and the other one
is in milliliters. In order to add these, they’ll need
to be in the same units. We could either change them both
into liters or both into milliliters. But we’re asked to give the answer
in milliliters, so it would be sensible to change them both into milliliters.

We should recall that in one liter,
there are 1000 milliliters. As we’re changing a quantity in
liters into one in milliliters, we’ll therefore need to multiply by 1000. So 3.15 multiplied by 1000 will be
3150. When we’re multiplying by 1000, we
move all of the digits three places to the left.

Now that our two quantities are in
the same units, we can add them. 3150 plus 6250 gives us 9400. Therefore, we can give the answer
in milliliters of 9400 milliliters.