The Excel formula `I_EOL_ACTBNK_IBAN` retrieves the IBAN number of the bank account of an account from Exact Online. Parameters: - `divisionCode`: division code. - `accountCode`: account code. - `useDefault`: whether to use the default contact person. - `formatCode`: bank account format. - `currencyCode`: currency code. - `countryCode`: country code. Returns: IBAN number of the bank account of the account.