Oh, Ye Of Little Faith
My first job was working as a cashier in a grocery store. I was quite book smart at the time, though pretty naive in many other ways. Math has always come easy to me and I quite enjoy it.
A couple of months into the job, I had a man come to my register and pay for $11 worth of groceries with a fifty-dollar bill. Then, the fun started.
Man: “I’d like my change as one twenty-dollar bill, one ten-dollar bill, three five-dollar bills, and seven one-dollar bills, please.”
I pulled the twenty and the ten.
Me: “Sorry, sir, but that comes to more than you originally paid. I could offer you one each of a twenty, a ten, and a five-dollar bill, and then four one-dollar bills.”
Man: “Uh, right, sorry. Then make it one twenty, two tens, a five—”
Me: “Whoops, just to stop you there, you only have $39 in change coming back and you’ve gone over it already. I can only do one each of a twenty and a ten-dollar bill; the rest has to be a five or just ones.”
Man: “Yeah, okay, sure. So, two twenty-dollar bills and then nine one-dollar bills will make it even.”
Me: “I apologize, sir, but I can only give you one twenty-dollar bill. After that, your remaining change is less $20. If you can tell me how you want the $19 broken down, I’m happy to do so.”
This continued for about twenty different iterations. The guy kept asking for bill counts which meant he’d get back $45 to $55. I kept just correcting him on the assumption he was just bad at math, and I was glad I could be so helpful to him because I was so good at math. Remember I said I was naive, right? I had never heard of a quick-change scam.
Finally, the guy relented and took his exact change of one twenty, one ten, one five, and four one bills and left.
At that point, my manager came over, shut down my register, and told me they needed to pull my drawer because I had just gotten scammed. I was confused, but she explained the nature of the quick-change scam to me once we were off the sales floor. I mentioned that I thought the guy was just really bad at math, but it was okay because I knew he’d gotten exact change back and nothing more.
Manager: “[My Name], you don’t have to be embarrassed. They target new cashiers and they’re really good at these scams. You got fooled and we’re just going to document how much he stole for when we file the police report.”
Me: “Seriously, [Manager], he got his exact change and nothing else. I was keeping track the whole time.”
Manager: “[My Name], we’ll talk later. I have to write you up for the drawer being off, but it will just be a verbal warning because these scammers are so good. Just let me count the drawer now and you’ll see.”
I counted by watching over her shoulder. She compared the total to the report and found that my drawer matched to the penny.
Manager: “Hmm, that can’t be right.”
She counted the drawer again.
Manager: “No, I know that guy. He scammed me the last time he was in. I know your drawer must be off.”
She counted it a third time, and the drawer was still perfect.
Manager: “I don’t get it. He scammed you. I watched how many times he changed the bill count. No one could keep track of that.”
Me: “Umm, you know I’m studying calculus, physics, and computer programming at [Local College], right? I’m really good at math and assumed that dude was really bad at it. I felt bad for him since I had to keep correcting him on which bills added up to $39.”
Manager: “You got lucky, but I don’t know how. I’m going to pull the video for the police anyway. Get back to work.”
And that’s how I learned about the quick-change scam while totally ruining some scam artist’s flow with math.