In my recent past, I was running through my day allowing only a few moments to eat a burger in the truck between visits. This is normal. We can discuss diet, just don’t look at what I eat. Anyways, one added benefit of this burger was that it was a single dollar. Throw in a bit of government for a dollar eight total. That makes it a simple dollar, nickel and three pennies. I had the dollar. I had the pennies, but only had a quarter. That seemed easy enough for me. Twenty eight minus eight equals what class? Yes, you near the window…
I presented the money to the cashier who disregarded the pennies and left them on the counter. I saw her look at the register and then start to count out change. She goes for the dime, then nickel and pennies, then looks over her shoulder, “I need some pennies.” You know, like those strange round disks I was trying to give her.
I picked up the three pennies and presented them to her – again.
She looked at them like they were drachmas and I applied a little math – “you can give me two dimes.”
She looked at the register, looked at the change and apparently added 3 to 17, realized that I told the truth, and pulled out two dimes. I finally had my change. She now had a few more pennies and repeated her request for pennies over her shoulder again.

If you have any wonder how Zero got back into Air Force one, I present this case as one possibility.