Mathemagical

Cashier: “Your total is $10.86.”

(I look in my wallet, and see a $20, a couple of ones, and some change. Since I don’t want a ton of small bills and change, I give the cashier $21.11. The cashier stares at the money for a minute, and then tries to hand the $1.11 back to me.)

Cashier: “The total is only $10.86.”

Me: “I know.”

Cashier: “You gave me too much money, ma’am. I only need the $20. You can keep this.”

(The cashier tries to hand me the $1.11 again.)

Me: “I gave you that on purpose. I don’t want a bunch of small bills.”

Cashier: “But it’s too much.”

Me: “Just trust me, okay? Put the number into the cash register.”

Cashier: *doubtfully* “If you say so.”

(He punches it in. The register promptly indicates that my change is $10.25.)

Cashier: “Okay your change is… HOLY COW! Is $10 and a quarter! You did that on purpose!”

Me: “Yes, I did.”

Cashier: “How did you do that?”

Me: “Magic!”