def setID_format(number, characters_len):
    """
    Generates a str ready to attach to the 'main core' of the ID
    :param number: int of the ID
    :param characters_len: number of characters that the 'int part' of the ID has to be
    :return: 'int part' of the ID
    """
    id = ''
    for i in range(characters_len - len(str(number))):
        id = id + '0'
    id_to = id + str(number)
    return id_to
