The 3-6-3 rule is a slang term for an informal practice in banking, especially in the 1950s, 1960s and 1970s, that was the result of the industry’s uncompetitive and simplistic conditions.
The account balance represents the available funds or present value of an account of a particular financial account, such as a checking, savings or investment account.
The annual equivalent rate (AER) is the actual interest rate on investments, loans or savings accounts that can be obtained after compounding interest.