Errors because of unit conversion?

Just getting started with Dynamo (AU last week + GT class today). Trying to create a tool to grab the elevation of each floor in the project and push it to a string and then a parameter so that my floor tags can include the floor elevation (faster than placing tags and spot elevations). To get this info, I’m getting the elevation of the level that each floor is at and the Height offset from level and adding them together with an +SIUnit node. Somehow, it seems some values end up with errors while others are fairly clean (I model to 1/256" accuracy, so when I see values of 13/64" showing up that tells me there’s an error). I am also adding an elevation correction value to account for the lack of a shared coord system.

So I end up with index 2 = 1032’+0’+224’3" = 1256’ 2 13/32" (missing 19/32" somehow…)Capture. Any ideas? Is this just a result of metric to imperial conversion error? Is there a simple workaround for this (other than setting my Revit model to metric?) If this is something I will encounter regularly do I need to have a set method for converting all dimensions before doing anything to them in Dynamo?

CaptureApparently, there is a big problem with unit conversion. See attached image. Dynamo can’t seem to even add correctly…hard to trust it to do much if it cannot even do 3rd grade math.