Casio programming calculator. Its features are well-known. It calculates matrices up to 50x50. You can save formulas in it. It has a touchscreen. Very light use for testing, and it's done. Price: 500 SAR for the CG50 model. Also, there is another model slightly less than it, which has never been used. I bought it used, its model is fx-9860GII. Price: 350 SAR. Please only serious buyers. ( Phone number appears when clicking the contact button )