Answer:
Last week, a coral reef grew 19.5 mm taller. How much did it grow in meters?
Explanation:
So it's hard to explain but simply Milli witch is the symbol "m" is a unit prefix in the metric system denoting a factor of one thousandth (10 −3). So 19.6mm is 19.6*10^-3m. in other words 19.6 times 10^-3m
hope this helps sorry it's so complicated :/