def get_offer_floor(html_parser):
    """
    This method returns the floor on which the apartment is located.

    :param html_parser: a BeautifulSoup object
    :rtype: string
    :return: The floor number
    """
    floor_number_raw_data = html_parser.find(class_="param_floor_no")
    floor = ""
    if hasattr(floor_number_raw_data, 'strong'):
        floor = floor_number_raw_data.strong.text
    return '0' if floor == "parter" else floor