def x_pct_of_number(pct, number, *, precision="2"):  # pragma: no cover
    """
    Calculate what is the x% of a number.

    Arguments:
        pct        (int): percentage
        number     (int): number

    Keyword arguments (opt):
        precision  (int): number of digits after the decimal point
                          default is 2

    Returns:
        (str):  number

    Example:
    >>> x_pct_of_number(33.333, 90)     # what is 33.333% of 90?
    '30.00'
    >>> x_pct_of_number(40, 200)        # what is 40% of 200?
    '80.00'
    >>> x_pct_of_number(40.9, 200)      # what is 40.9% of 200?
    '81.80'
    >>> x_pct_of_number(40.9, 200, precision=4)
    '81.8000'
    >>> x_pct_of_number(40.9, 200, precision=0)
    '82'
    """
    num = number * pct / 100
    return "{0:.{prec}f}".format(num, prec=precision)