import re


def format_mile_info(n_str):
    """Format the mileage information extracted from the description.
    
    Args:
        n_str (str): extracted miles information from description in one line of the dataframe.
    
    Returns:
        str: formatted string to be converted in float
    """
    if(n_str[-1] == 'k' or n_str[-1] == 'K'):
        n_str = n_str[:-1] + '000'
    n_str = re.sub('[,.]', '', n_str)
    return n_str