Creating two equidistant edges (two "centered" edge loops) It's easier to explain what I'm trying to do with pictures.

I have this structure:


And I want to achieve this:


such that those two new edges are equidistant from the first, and the distance is set precisely (using the keyboard).

I've been doing this using two Edge Loop (Ctrl-R), but I need to do the math by hand, since it always counts the cut distance from the left. Is there a easier way?
Use Ctrl-B and then scroll (You can add more cuts that way):



You can fine tune the distance in the operator panel F6: