Ornery ?!?! That's deviant, low down, and high smellin' !!! I LIKE it!
In reality, the CASE statement is something that the original poster needs to know how to use since it opens all kinds of other possibilities that they'll need someday, but your bit of nifty math is both kinky and effective, so it is lots of fun the play with!
For some reason, possibly (probably) unjustified, I always feel like logic statements are less efficient than formula solutions. Just my bias, though I have to agree that the CASE statement is more readable. Without a comment, somebody looking at my solution wouldn't be able to immediately see its purpose.
If it's not practically useful, then it's practically useless.