We all learned math in elementary school, but doing adding and subtracting in daily life can still be a challenge. Our brains just aren't meant to be able to deal with large numbers. Keeping a desktop calculator handy will help you to take care of your business, not matter how many numbers you need to deal with. If you're doing your taxes or getting ready to pay your bills, you want those numbers to be exactly right, so use a desktop calculator and there will be no room for error. Desktop calculators don't cost very much, but you'll soon find out they can save you a lot of time.