def parse_gerber_number(strnumber, frac_digits):
    """
    Parse a single number of Gerber coordinates.

    :param strnumber: String containing a number in decimal digits
    from a coordinate data block, possibly with a leading sign.
    :type strnumber: str
    :param frac_digits: Number of digits used for the fractional
    part of the number
    :type frac_digits: int
    :return: The number in floating point.
    :rtype: float
    """
    return int(strnumber) * 10 ** -frac_digits
