CalcES 991 scientific calculator guide

Edit mathematical expressions directly

The calculator detects your device language automatically: Arabic for Arabic-language devices, and English otherwise. You can change the language in the workspace; your manual choice is saved on your device. Use the fraction key to enter a numerator and denominator, then tap the part you want to change. Arrow keys move the cursor, and selection lets you copy or delete part of an expression. Input and results appear separately.

The editor displays fractions, roots and powers as mathematics. Session history displays successful calculations and lets you recall their original inputs and settings. An unfinished expression does not show a completion warning as you type. Press = when you are ready to calculate.

Fractions, roots and powers

Use COMP mode for ordinary calculations. Enter a fraction with the fraction key, or insert a root and place its argument inside it. SHIFT selects secondary functions, while ALPHA provides the available variables.

• 1 ÷ 2 + 1 ÷ 4 = 0.75
• √9 + 2³ = 11
• 200 × 10% = 20

A percentage means division by 100. It does not implicitly add a commercial percentage to the preceding number.

Trigonometry: degrees and radians

Check the angle unit before using sin, cos, tan or their inverse functions. In DEG mode, sin(30) = 0.5. In RAD mode, sin(π ÷ 2) = 1. Changing the angle unit changes how the next calculation interprets its input.

Scientific functions include base-10 log, natural logarithm ln, absolute value, factorials and hyperbolic functions. Real logarithms and roots require inputs within their mathematical domains.

Definite integration and differentiation

Enter a function of x, open the integration tool and set the lower and upper bounds. For example, the integral of x² from 0 to 1 is approximately 0.33333333333333. Integration is numerical and requires finite bounds and a continuous function without poles; it is not a proof of convergence.

Choose the secondary d/dx function to differentiate. The derivative of x³ is 3x², which evaluates to 12 at x = 2. You can obtain a symbolic derivative and optionally evaluate it at a point.

Matrices and equation solving

Select MATRIX in the MODE menu and enter values in the workspace. Available operations include the determinant, inverse and multiplication. For example, the determinant of [[1, 2], [3, 4]] is −2. A singular matrix has no inverse.

The equation tools support one numerical root inside a suitable interval, linear systems with two or three unknowns, and polynomials up to degree three. A numerical root search does not find every possible root of an equation.

Complex numbers, statistics and number bases

CMPLX supports Cartesian complex arithmetic and polar conversion. STAT provides the mean, standard deviation and linear regression. BASE-N converts between BIN, OCT, DEC and HEX, with AND, OR, XOR and NOT on signed 32-bit integers.

Calculations use math.js and the editor uses MathLive. Some algorithms, including complex arithmetic and polynomial roots, use machine precision. Approximate results do not imply unlimited accuracy; independently check results that matter.

Privacy and installation

Calculations run on your device without sending expressions to a calculation server. History holds calculations from the current session. Your language choice and rating reminder preferences are saved locally. See the privacy policy for details.

On Android, the install button opens the app on Google Play. Supported browsers can install the web app; on iPhone, use Add to Home Screen from Safari’s share menu. Once the web app’s resources have loaded and been cached, calculator functions can run offline. External links still require internet access.

Support and development

Maaoun Studio · jy906675@gmail.com

CalcES 991 is an independent app and is not an official CASIO product.