Calculators: an exercise in mediocrity

So heres an idea for a rant i've had for a long time, so whats the point of using calculators in school? In 4th grade when we were learning division and such we weren't allowed to use them, but now we're allowed to use them for almost everything, its stupid. When all the computers fail, how will stores calculate prices? They probably can't write it out because they probably don't know how too. It's stupid, or rather its making us stupid. They let us use calculators for stuff we could do in our head probably if we thought about it or wrote it out. Its ridiculous.