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

First, people tend to get confused over the "double the money" part and not know how to put it into an equation. Just make something up, and then double it. Or just $1 and the $2 for the double. It doesn't matter about that part.

Is that the issue, and does that get you on your way?

If not, do you know if this is supposed to be compounding or not? And, are you using algebra or not?

I'm assuming that the money is compounded annually.

P = principal interest

like morgaine says, do an example.

$100

after 1 year

$106.50

after 2 years

$113.4225

so on and so forth.

the actual formula can be found

Regular Compund Interest Formula

hint: if you put in P amount, and you want to double it, the end product you want is 2P

... 2P or NOT 2P