Math is one of those subjects that has a distinct right and wrong. In English class, you can write an essay that argues basically anything you want as long as you can use the text to support your arguments. In art class, there is so much room for creative liberties, even if you're given a more specific assignment. In math, not only is there one right answer, but oftentimes, teachers make their students show their work, and if it's not done the way they taught it, they'll take points off. Talk about a dictatorship!
I distinctly remember having to know that 0/1=0 and 1/0=Undefined during my high school math courses. Why I had this memorized is beyond me now, but nevertheless, it sticks in my mind. One mother of an elementary schooler recently went viral after finding out her son's teacher told him that 1/0=0. When confronted, the teacher and the principal doubled down.