How does Casio fx-99 1es plus distinguish authenticity?

Press and hold the four keys 1 0-= and then release 1 (note: do not release the other keys). If 1cos (is true, but only 1 is displayed. Using the principle of keyboard scanning circuit! There is also a simple way to distinguish between genuine and fake products: 1, the genuine product has the word "Casio" when it is turned off, but the fake product does not; 2. Genuine products have anti-counterfeiting labels, which are exquisite, but counterfeit products don't, or although they do, the printing quality is poor and the patterns can't move with the light; 3. The calculation results of genuine products can be displayed in fractions, while counterfeit products can only be displayed in decimals; 4, the quality of genuine products is exquisite, and counterfeit products are generally rough.