In theory.
This actually works well for a certain number of buttons, if you can find the right resistors. The problem is finding the right values of fixed resistors to handle the number of buttons to give you unique numbers (well - "ranges" - since resistors aren't perfect) for each button press (or combo).
If you could set it up so that the resistances were calibrated in powers of 2 (perhaps using trimmers?) - or something close (fixed or adjustable, you would want ones with tight tolerances)...
After going thru that much trouble, though, it might be easier to do with some kind of multi-bit BCD encoder chip or something like that...