While we heard it said, and more often the more specific realistic version was that you wouldn’t always have a calculator on the tests through college, there is a few more proper reasons that still apply. Knowing how the equations work, as well as that they exist. You can look them up and will probably build an excel spreadsheet at work but even using AI today it’s vital that you can check the work. It also effects your brain development. If you’re running calculations in your head while doing them by hand it develops parts of your brain and eventually lets you think in math terms. The effort required probably also does a good job of sorting people out of career paths. I don’t want planes flying around me that were “vibe calculated”