Most banks use a 4-digit clearing number followed by an account number. If you have an account in Swedbank where the clearing number starts with the digit 8 and the account number consists of 8 or 9 digits, you need to add one or two zeros at the beginning of the account number so that the total becomes 15 digits (including the clearing number).
Example: CCCCC 0XXXXXXXXX (C = Clearing number, X = Account number).