def noy(Ky, M, rho, w):
    """
    Calculates the number of units at the plate.
    Parameters
    ----------
    Ky : float
        The masstransfer coefficent Ky, [kmol / (m**2 * s)]
    M : float
        The molar mass, [kg / kmol]
    rho : float
        The destiny , [kg / m**3]
    w : float
        The speed [m / s]
    Returns
    -------
    noy : float
        The number of units at the plate, [dismensionless]
    References
    ----------
    Дытнерский, стр.239 формула 6.35
    """    
    return Ky * M / (rho * w)