I used to work as a cashier at Kroger when I was in high school. It was my first “real” job and taught me a lot about money management (namely how to get it honestly). I also learned the value of education in that I could calculate change before I even entered the customer’s cash payment into the register.
Now, I like to mess with cashiers by giving them odd amounts that will result in desirable change. Today, I ordered lunch at the Flying Cow Cafe here at the National Weather Center, and given a total of $5.64. I didn’t have 64 cents, but I did have change for 14 cents, thus I gave the cashier $6.14. The cashier took my money, stared at it, looked at me, then entered 6-1-4 into the register. The till opened and $0.50 appeared on the screen. She literally stared at the screen for a good 3 seconds before depositing my cash, then stared another two seconds at the till before getting two quarters and handing them to me.
A good cashier will just enter the money and get my change without hesitation. A great cashier will see what I did and comment about my mathematical skills. A run of the mill cashier will do what happened above.
Kids, learn math. You will eventually find out that you will use it every day.