Yes that is the reserve ratio, but that is not fractional reserve banking. It means that once they loan out that 9,000 dollars from 10,000 they can report to have MORE in reserve than that 1,000 dollars. They can say they have actually 1,500 in reserve (they don't). That means they have a FRACTION of the reported reserve.
Let's run through an example of what happens with money in a fractional reserve form of banking.
I earn or otherwise get $!0,000. I don't need to spend this money right now but may want it later so I loan it to the bank (open an account and deposit the money with them). The bank has a reserve requirement where they are requilred to keep ten percent of their deposits on hand- this is the "fractional reserve" they are required to keep and where the term comes from. That means they can loan out up to $9000 of that money. I had $10,000 but now have none. The bank has $10,000 and I have an IOU from the bank for that amount.
Bill decides he needs some money so he goes to the bank and asks them for a loan. He takes out $9000- the maximum the bank can currently loan out. Now the money is as follows:
I have no money but am owed $10,000.
The bank has $1000 but owes me $10,000.
Bill has $9000 and owes the bank $9,000. Money supply is still $10,000.
Bill decides to wait on his purchase so he puts the $9000 in the bank for a while. He has created a deposit for $9,000. The bank gives him an IOU for the amount. He is currently neutral- he owes the bank $9,000 but they also owe him $9,000. Now the bank can make a loan against that deposit. With a ten percent reserve requirement, they can now loan out an additional $8100- keeping $900 on reserve. Carl comes along and wants to borrow money so he takes out that $8100 in a loan. He takes the money and gives the bank an IOU.
This is the current money status:
I have no money but am owed $10,000.
Bill has no money but owes and is owed $9,000.
Carl has $8100 and the bank has $1,900. Total money is still $10,000. Debt has grown but the money supply hasn't.
Things get messed up when somebody decides to take their money out of the bank. Bill decides to close out that deal on the car he wanted so he takes out his $9,000. But the bank doesn't have it. They can't make money out of nothing so they have to get it from someplace. That can be by borrowing money from another bank. Or attracting in another $9,000 in deposits. Or they can borrow money from the Federal Reserve. Or they can call in an outstanding loan. They bank will also have more out in loans than their deposits allow- they have gone below their reserve requirement. They cannot make any loans until that is fixed. Giving Bill his money temporariliy increases the money supply but the bank borrowing (or taking in more deposits which is also borrowing) shrinks it back down again.