def date_string(day, month, year):
    """Build a date string using the provided day, month, year numbers.

    Automatically adds a leading zero to ``day`` and ``month`` if they only have
    one digit.

    Args:
        day (int): Day number.
        month(int): Month number.
        year(int): Year number.

    Returns:
        str: Date in the format *DD/MM/YYYY*.
    """
    return '%02d/%02d/%d' % (day, month, year)
