Explain the rules for multiplication and division to convert units. how do you know when to multiply and when to divide to convert untis of measurement?

Well, units divide and multiply just like numbers. That's why Area is in units of  distance squared (cm × cm = cm²) and volume is cubic distance (m × m × m = m³).

Likewise other mathematical operations can be performed on them, including division where they can cancel out of the equation.

For instance, a rate, speed, slope or conversion factor is usually one unit divided by another unit. Like so...

speed = 5 meters per second


If you are given a distance traveled, let's say 100 meters and asked to solve for time it takes to get there. You would divide by the speed so that meters cancel leaving only time.

** Of course to divide by a fraction is to flip and multiply so really you're just multiplying by it, making sure the same units are diagonal and cancel out like so:



Hope this helps!