**I went to the local pizzeria on a recent Saturday night. The cost was $10.50; I gave the cashier a $20 bill and a $1 bill. But he gave me back the dollar bill, and then gave me change for the $20, which was $9.50.**

As it turned out, they were out of five-dollar bills, so he was going to give me nine one-dollar bills and 50 cents. Seeing this, the owner yelled, “Just charge him [me] ten bucks.” Clerk says, “But I’ve already closed the register.” Owner overrides register to reopen it, puts back the $9.50 and gives me a $10 bill.

Of course, I gave the clerk $21 in the first place so he would not have to give me a bunch of ones. If you’ve ever been in retail, you know that you don’t want to give away ones if you can help it, and certainly not nine of them. I knew that, the owner knew that, the clerk, not so much.

***

For some reason, I’m reminded by a story from long ago, where a guy I knew wanted to buy milk and a newspaper. At the time the milk was 99 cents and the newspaper, 35 cents. But the register wasn’t working properly, and couldn’t give the total, though it could give change. The problem is that the clerk couldn’t figure out the change from $2, because he didn’t know the total of the purchase.

The guy tried to explain: “99 cents is a penny less than a dollar, so it’s $1.34. These are non-taxable, so it’s $2 minus $1.34 is 66 cents.” This was too complicated.

I worry that when the computers all go down, no one will know how to add and subtract, never mind do multiplication and division.

***

I was watching the NBC Nightly News and saw this story: Gas Prices Drop to Lowest Level in Nearly Four Years, using the picture. I had to write to them.

“The average price drop is NOT 30% [as Brian Williams said], itâ€™s 30 CENTS, as the graphic showed, from $3.34 to $3.04,” I noted. If it had been 30%, the drop would be about $1.

***

The Daughter is doing order of operations at school. At a website quaintly called Math is Fun, it reminded me that the order in which one does math problems is:

P

Parentheses first

E

Exponents (i.e. Powers and Square Roots, etc.)

MD

Multiplication and Division (left-to-right)

AS

Addition and Subtraction (left-to-right)

I’ll admit to forgetting where the exponents fit, exactly.

**So what is the answer to the item posted above?**

102

In the cashier’s defense, it’s hard to think straight by the end of a shift. I’ve found myself making goofy errors in jobs like those because I’m tired or stressed. Apparently there’s research on how shift work slows your mind: http://www.bbc.com/news/health-29879521

On the other hand, watching my students use a calculator on problems like “9-7=”…

Don’t know if it were the end of the shift. It was only 6:30 pm. Maybe they didn’t get enough fives and tens from the bank to keep in the drawer. Always tricky on the weekend, as I’ve experienced.

Don’t get me started on this! Once I bought a bucket of chicken at KFC and somehow the tax ended up being half of the price of the bucket. I tried to explain that the amount of tax could not possibly be 5% of the price of the chicken. The cashier just shrugged and said, “that’s what the cash register says.” Genius.

5 percent seems like a reasonable tax, but I can’t figure out how much the chicken cost. Math is hard!

One time I was working at Pizza Hut. It was a Sunday, and we’d just opened. First customers are a jerk guy and his girlfriend. He wants to impress her, so when they come up to pay, he flicks at $100 bill on the counter. At this point all I have on hand are $5’s and $1’s, so I ask him if he has anything smaller. He smirks and says no, so I nod and count out his change. All $88 of it. In singles. He tries stopping me a few dollars in, and I said, “That’s why I asked you for a smaller bill. You’re the first customer cashing out, and I’m not running a bank here.” I loved foiling his plan to look cool in front of his girl.

I was once in a situation of checking out at a store when the cash register pooped out (this was some years back, I suspect now they’d just tell everyone to come back later). I wound up having to tell the cashier how you count back change. I have never worked retail, it’s just something we were taught in basic school math.

I’ve actually had to remind my college students about PEMDAS. I think that working a lot with programs like Excel to do calculations tends to make you forget stuff like that.

I’ve also had dining companions look at me like I was some kind of a wizard for being able to figure out a percentage tip (15%, which was standard at that time) in my head.

It’s just math. I learned it when I was still wearing braces on my teeth….

I used to run into the same situation as Jaquandor all the time working at Hollywood Video. It was in a very well-off area, and on Friday (payday) we’d get a ton of office jerks who’d come in and decide the video store was a great place to break a hundred dollar bill on the way home. A hundred dollar bill casually handed to me on a $1.99 rental… I’d always make sure to take the money back to the safe in the office and make sure it was as inconvenient for them as it was for me.

Which is why lots of places these days don’t take bills larger than a $50 or even a $20. Well, that reason and the fear of counterfeits.