math is HARD (even with computers (redux))

Today I decided I'd use some of my large pile of change-jar coins to pay my way on the DART. Since they've got a 20-coin "rule" on the manned window, I figured I'd feed my coins to the machine. Which, er, broke. With a message like "can't display template 82" or thereabouts. It eventually timed out whatever it was doing, but would not allow me to insert more coins, so I cancelled the transaction and tried again, this time with less coins. And I broke it again. And the third time, I used more high-denomination coins and less of the crappy 5¢ ones, and got my ticket just in time for the arriving train - because otherwise I'd actually have taken a picture to capture the moment, and possibly have taken the time to figure out exactly how many coins break the system. Seriously, though. I wrote vending machine logic in college, in FORTRAN, as part of my college girlfriend's project. It's not hard. Getting it this badly wrong is pretty dumb.