Can any of the younger generation do mental math?

Once again I encountered it: I had a bill that was $16.52 for lunch at a fast food place. So I gave the cashier a twenty, a single, and two cents. She looked at me like I was crazy, and counted the cash twice. She almost shrugged as she put my amount into the cash register, and I could see how surprised she was when the change amount came back as $5.50. As she handed me the change, I could see on her face the question “how did he do that?”

This happens far too often. My wife says it is because children no longer really learn math in school. They get to calculators quickly. Memorize the times tables? Do long division by hand? Figure out percentages? It seems like these are relics of the past, like learning cursive writing. This is elementary school stuff, and it looks like one can graduate high school without learning them.

Mental math seems to have gone the way of the Dodo bird.