Heck of a deal

I went to get Buddha some dog food this morning and I think I almost received the deal of a century. I found a bag that was marked 20% off because it had a hole in it that had been taped up. The bag was supposed to contain 40 pounds of dog food, it sure felt heavy so I guessed that it hadn't lost much, and what the heck 20% off is pretty good. So I get to the register and the lady has no idea how to take 20% off, so she calls a manager. The manager comes over and types in some stuff and walks away. The lady turns to me and says "Ok, that will be .21 cents." That was a $35.00 dollar bag of dog food, and while I'm not the best math student out there even I know that .21 cents was a little low! I told her I didn't think that was right and she was REALLY confused, she acted like she didn't want me to say anything and just walk away. So she called the manager back up and we got it straightened out, I got a true 20% off. Ahhhh, don't you just love people's grasp on math?