Display expression same as textbook. Arabic and english languages Viewing and editing of input data in list format, showing data groups (x-data, y-data, frequency and surrounding data). Quick and easy recall of previously executed formulas for editing and re-execution. 10-digit mantissa 2-digit exponential display. High resolution secreen provides beautiful looking graphs every time. Designed and engineered for easy operation. Other Features: Two way power 542 Functions Full Dot Display Plastic Keys Integration / Differential Equation calculation Matrix calculations / Vector calculations Complex number calculation CALC function / SOLVE function Base-n calculation Fraction calculation Combination and Permutation Logarithm log List-based STAT data editor Standard deviation Paired-variable statistics regression analysis Logical operations Table function 40 scientific constants 40 metric conversions (20 conversion pairs) 9 variable memories Main Specifications for the fx-991AR X Trigonometric and inverse trigonometric functions, logarithmic and exponential functions, power and root functions, hyperbolic curve and inverse hyperbolic curve functions, inverse functions, factorials, pi, permutations (nPr) and combinations (nCr), coordinate conversion, statistical calculations, time calculations (sexagesimal), table and dual table functions, answer memory, random number generator (including random integers), engineering notation, number rounding, thousands separator display, multi-replay function, error position display, multi-statement function, undo function, auto power off fx-991AR X simultaneous equation (2-4 unknowns), polynomial equation (degree 2-4), inequality calculations (degree 2-4), ratio calculations fx-991AR X Spreadsheet, QR code generator, complex number calculations, base-n calculations (base-2, 8, 10, 16), logical operations, matrix calculations, vector calculations, CALC and SOLVE, sum total calculations, numerical differential and integral calculations, scientific constants, unit conversion, engineering symbols Number of Digits10-digit mantissa 2-digit exponential display Memories9 memories (1 independent memory 8 variable memories) Power Source and Battery Lifefx-991AR X model: Two-way power system combining solar cell and 1 LR44 button-type battery 2-year battery life (if used 1 hour daily) Auto Power OffAfter approx. 10 minutes of non-use Dimensions and Weightfx-991AR X model: 11.1 × 77.0 × 165.5 mm; approx. 90 g (including battery) Main AccessoryHard case