Using Casio Calculators to calculate wavelength for radio amateurs. Which modern calculator is difficult to use for this. The Casio FX991CW classwiz gives incorrect answers until you use BIDMAS entry which is really awkward compared to the existing non classwiz calculators.
If you want a modern calculator for these types of radio or engineering calculations, stick with fx300ES Plus or fx570ES Plus2 style calculators etc, steer clear of the Casio calculators with model numbers ending with CW. Look for the EXP button and the x10x button type calculators.