How old are you?

Question: If you don’t have the knowledge to be able to count change back how do you have any money at all? What you just trust that the teller is correct. Bought a parka once it was $47 gave the teller a $50 bill. She put it in the till and gave me change for $100. I said that’s to much change. She wheeled around and BARKED at me you trying to tell me how to do my job. Blink blink I said no took the parka the receipt and $53 and went home. Liked to have seen her face at cash out lol