posted by Elizabeth .
How do I know when to multiply and when to divide when converting to metric or from?
OK, good question. You know whatever units you start with will have to be divided by something across the fraction bar.
450km ( xxx/yyy) so km will be the units of yyy.
450km* 1000m/1km will work. Now I am in meters, and I need to get to miles. Hmmm. I know there is 1609m per mi, so
450km*1000m/1km * here I put m in the denominator so it divides out...
450km*1000m/km * 1mi/1609m and that does it.
Thank you, I'm going to practice and see how I do.