I have the FX-991 DE X purchased for the university, because we have to type long and cumbersome formulas expressions increasingly. Main reason for buying was the improved display. The build quality is still good, but just as far as the key pressure point, not outstanding. The key press is relatively vague, but a quick operation does not detract. The summing up points in the exams went blind and very quickly out of hand. The display stands out completely by the high resolution, so that even more complicated formulas can be entered clearly and precisely notice clamp errors faster. Operation is intuitive, and the printed manual contains all the essential functions. I have not yet tested the QR Code function. Especially the power from the solar cell is very convenient. Whether the light is sufficient indicated by a small icon and the problem of empty batteries in exams should therefore no longer be a problem.
Overview: + Good display + Good workmanship + High-quality optics + Printed manual + Solar cell with battery backup
- Spongy key pressure point - Protection slider has a relatively large distance from the screen (although he now protects against pressure in the pocket) - (Subjectively) bother me the serifs in the representation
Conclusion: For the university or the school where graphical calculators are usually not allowed highly recommended. But necessarily should be noted the functions. Especially matrices and solving equations are often not permitted.
