A crystallographer measures the horizontal spacing between molecules in a crystal. The spacing is

16.7

nm

. What is the total width of a crystal in millimeters

105

molecules across? Write your answer as a decimal.

That's what I was thinking. I wasn't sure if we were precisely interested in finding the molecule's width as well (which I didn't know how to do but had a vague idea of how we might accomplish it). If this is just for unit conversions though, your answer seems sufficient. You just need to convert nanometers to millimeters.