Creates a percentage string representation from the given `number`. The
    number is multiplied by 100 before adding a '%' character.

    Raises `ValueError` if `number` cannot be converted to a number.

def to_percentage(number, rounding=2):
    """Creates a percentage string representation from the given `number`. The
    number is multiplied by 100 before adding a '%' character.

    Raises `ValueError` if `number` cannot be converted to a number.
    """
    number = float(number) * 100
    number_as_int = int(number)
    rounded = round(number, rounding)

    return '{}%'.format(number_as_int if number_as_int == rounded else rounded)