If you deposit money today into an account that pays 6.5 percent annual interest, how long will it take for you to double your money?

It will depend on how your interest is paid, daily, weekly, monthly, qty. etc. But a rule of thumb is divide the interest rate into 72 and that will get your number of months for your money to double. In this case about 111 months. Or just shy of 10 years... now if you can find a 10% rate of return, then its only little more than 7 years.. Good Luck !