An account stated may also be established when the debtor retains the statement of account (for example the bill or invoice) without objecting, for a reasonable length of time. "Reasonable" is determined by looking at the surrounding circumstances. An account stated is in the nature of a kind of settlement between the parties, such as when a person receives a bank statement, is capable and even obligated to check the math within a specified period of time, otherwise the account as between the parties is thus "stated." The key element is either the express agreement or an agreement implied by law under all the facts and circumstances.