[css3-values] multiplying and dividing complex units in calc?

Based on the spec I can't discern whether the following will work as
expected:

calc(20px / 1s * 20s) => 400px

I'm concerned about this because storing ratios as intermediate values in
variables is incredibly useful. So once we have variables I'd like to be
able to store `calc(20px / 1s)` into a variable and then use that in
multiplication and division to translate between two otherwise unrelated
units.

Chris