If I pointed out that the speed of light in m/s is exact and the number of metres in a yard is exact and proceeded to give the exact value of the speed of light in imperial units

That's not reasonably called OR on Wikipedia either. See: http://en.wikipedia.org/wiki/Wikipedia:No_original_research#Routine_calculations

For some time, they claimed that converting exact values as rational numbers (as opposed to conversions with a finite number of sigfigs) is not a routine calculation. (To be honest, I'm not sure I remember what eventually happened. [goes to check] Oh, yeah. The footnote stayed because we did find a citation. Not that I'd normally consider the personal website of a cryptographer as a reliable source, but still.)