<p>A nanometer is one billionth of a meter (10^-9), while a millimeter is one thousandth of a meter (10^-3). So there is 10^6 or 1,000,000 nm in a mm.</p>
<p>A millisecond is one thousandth of a second, so there would be 1000 of them in a second.</p>
<p>A picometer is one trillionth of a meter (10^-12). There is no reason for the 3.5 to change. All you need to do is figure out the proper power of 10. 10^-9 divided by 10^-12 is 10^3 or 1,000. Just think about it and you can see your answer is wrong. Picometers are smaller than the original measurement you are given; there wouldn’t be a fractional number of them.</p>
<p>Here is a web site with metric prefixes: <a href=“http://www.unc.edu/~rowlett/units/prefixes.html[/url]”>http://www.unc.edu/~rowlett/units/prefixes.html</a></p>
<p>It would be useful for you to review the rules for multiplying and dividing with positive and negative exponents. Here is a web site: <a href=“http://www.edinformatics.com/math_science/scinot.htm[/url]”>http://www.edinformatics.com/math_science/scinot.htm</a></p>
<p>I hope this helps. It is important at the outset to learn how to make these calculations. I’m surprised the subject isn’t covered in your text. Perhaps it is in an appendix to your book?</p>