Math Trouble

So I found out something interesting about my membership discount card with a bookstore chain. I bought it with part of the gift card my sister gave me for Christmas, reasoning that I would thus stretch her gift out over a whole year and get the most for her money. I'm thoughtful like that.

Well, the other day I saw an item at that store that I thought I would purchase, and noted that as a new release, it was already 20 percent off. The sticker (which is also the inventory control tag -- clever) said that members saved an extra 10 percent.

Did some rough math in my head and figured that meant that the $14.99 item I wanted to buy would be discounted about $4.50 and thus cost me $10.49. But when I actually looked at my sales receipt, it had rung up as two separate discounts: The 20 percent was taken off the $14.99 as $3 (they round up), and then my 10 percent member discount was taken off of that figure as $1.20 off, leaving a figure of $10.79 and a total discount of 28 percent, rather than 30.

Now, even I'm not cheap enough to quibble over thirty cents, and I'm also pretty sure there's a clause buried somewhere in the membership card info that says they'll discount things this way so I'm not claiming I'm being cheated. And for the company's part, I'm pretty sure that when you spread that 30 cents, or more, if the item's price is higher, over the millions of books they do sell, it adds up for them.

It was just a kind of slightly disappointing feeling, like hearing a friend say you had to divvy up change found in a couch with him because you found some of it on the side he had been sitting on, even though he hadn't lost any change from his pockets. Oh well -- even bookstores can have feet of clay.