I use a calculator all the time. I can do problems in my head but I prefer to use calculators rather than waste brainpower on thinking of an equation in your head that can be done simply with a calculator. However, I do disagree with using calculators if you don't understand the problem. I believe using calculators are a sort of achievement that you know what you're doing. If you know what you're doing, why waste your time thinking out the problem in your head when you can get it done a hell of a lot faster with a calculator?
Think of using a calculator as an earned right. If you haven't learned the material, learn it, so that a lack of a calculator isn't so much of a panic. It may take you longer to do tests without them but you can do it if you practice working without one. That way, when you're simply doing homework, you can use a calculator all you want, knowing that it comes with no consequence! :D
