Sounds like the kind of teacher I'd get along with.
At your hypocrisy point, she's a teacher. She never said that it was faster to do mental math than use a calculator -- she's saying that you shouldn't need a calculator to solve the problems. She doesn't need one either, but it's faster for her to check the work using a calculator.
At least you don't get the excuse I used to get as a kid. "What are you gonna do, carry around a calculator with you everywhere you go?"
Guess what: it turns out that not only do I do that; you do too.