I don't know where you went to school, but in my college I was allowed to use calculators on the math tests. I never did because I quickly realized the professors intentionally wrote problems such that doing math in my head would be easy. Those who used a calculator missed the important crutch of, 'oops, this math is getting hard - That must mean I'm making a mistake' and go back to fix the problem.

Physics and chemistry, dealing with real world constants that are often not particularly around easy numbers, you pretty much need a calculator in order to get anything close to a correct answer. But even then, the correct thing is to simplify without a calculator first before plugging the numbers in.