One of the very nice features of the metric system of measurements is that there is a set of standardized prefixes that can be applied to any of the units. Some of the more common ones are
.. micro- . . . one millionth
.. milli- . . . . one thousandth
.. centi- . . . .one hundredth
.. kilo- . . . . .one thousand
Thus, one millimeter is 1/1000 = 0.001 meter. There are 1000 of them in 1 meter, so
.. 16 m = 16000 mm