Tyler has 2 liters of water and drinks half of it. how many milliliters of water does he have left?

Firstly, if he drinks half of the water, the amount of water he has left is 2 - (0.5*2) = 2 - 1 = 1L.

Milli is the SI prefix for 10^-3, or one-thousandth. This makes 1 millimetre one thousandth of a metre, and consequently one millilitre is one thousandth of a litre too. The converse is that there are 1000 millilitres in one litre.

The answer is then 1000ml. I hope this helps you :)