Scientific calculator plus 991

Review by eFreeware

Students working through math, physics or engineering coursework are the people most likely to want Scientific calculator plus 991. The app gathers five calculator modes under one roof, so a single install covers the arithmetic you do in class, the algebra and calculus you do in problem sets, and the graphs you draw to check your reasoning. With more than 50 million installs and a 4.8 average from over 562,000 ratings, it has clearly found a large audience among learners.

What appeals to me is the breadth. Instead of one calculator stretched thin, the developer has built separate modes that mirror the machines students already recognize: a basic 300 plus, an advanced 115 plus, a scientific 991, a scientific 991 plus and a graphing 84 plus. Each mode is pitched at a different level of work, and the keyboard layout is designed to match the 300 es plus and 991 ex or es plus models, which should make the transition from a physical calculator fairly quick.

The app is free to install, carries ads and offers in-app purchases. That combination is worth knowing before you commit, though it does not change what the calculators themselves can do. For a student who needs a reliable daily tool, the range of functions on offer here is the main draw.

Fractions, logs and everyday arithmetic

The basic calculator 300 plus and the 115 plus handle the sort of work that comes up most often: percentages, powers, roots, trigonometric functions and logarithms. Fraction support goes beyond simple division, converting between fractions and decimals, handling mixed fractions and solving fraction problems. For anyone working through a textbook chapter on rational numbers, that is a meaningful convenience.

The 115 plus mode steps things up by combining what the developer calls a hyper calculator with a simple scientific one. It handles calculus, linear algebra and complex numbers, and results can be shown in polar or rectangular form. Matrix and vector operations are included as well. That makes this mode the natural home for the linear algebra assignments that show up in the first years of an engineering or science degree.

I would expect most users to settle into one or two of these modes and stay there. The basic mode covers day-to-day arithmetic, while the 115 plus is there for the heavier material. Having both in the same app means you are not switching between tools when a problem changes shape.

Equation solving and symbolic work

The scientific 991 plus mode includes an equation solver that handles quadratic and cubic equations as well as systems of equations. The developer says it can solve any polynomial, which is a broad claim, but the underlying capability — finding roots of polynomial equations — is exactly what students need for algebra and pre-calculus work. The same mode covers derivatives, integrals, square roots, factorials and pi calculations.

The standard 991 mode adds a different set of tools: calculations with an effectively unlimited number of digits, prime factorization, random numbers, combinations and permutations, plus GCD and LCM. These are the functions that come up in number theory, combinatorics and discrete math courses, and having them in a calculator rather than a separate script is convenient.

Symbolic calculation is handled by a built-in computer algebra system. That means expressions can be manipulated in symbolic form rather than reduced to decimals immediately, which is useful when you need to keep an answer exact. Between the equation solver and the CAS, the app covers a lot of the ground that a graphing calculator would traditionally handle.

Graphing and visualization

In 84 plus mode it plots functions, including polar, parametric and implicit ones. That range matters because implicit graphing in particular is not something every calculator app offers, and it is often required for conic sections and other curves that cannot be written as a simple y equals f of x.

Beyond drawing, the mode supports tangent lines, tracing, derivatives, roots, and finding minima and maxima. These are the tools you reach for when you want to understand the shape of a function rather than just evaluate it at a point. The developer describes the mode as simulating the graphing calculator 83 and the t1 84 and 84 plus, so the workflow should feel familiar to anyone who has used those models.

For a student preparing for an exam or checking homework, being able to see the graph alongside the algebra is often the difference between getting an answer and understanding it. This mode is the app's strongest argument for replacing a dedicated graphing calculator.

What else is included

The app bundles a few extras beyond the calculators themselves. There are math and physics formula references, a unit conversion tool, theme and font options, and programming features. These are supporting pieces rather than the core, but they add value for someone who wants a single reference point during study sessions.

The formula sections in particular could save time when you need to check a relationship you have half-remembered. Unit conversion is the kind of utility that gets used more often than expected, especially in physics and engineering problems where units have to be consistent. The theme and font settings are cosmetic, but they let you adjust the display to your preference.

The developer is still actively working on the app rather than leaving it as-is, which is reassuring for something you might rely on throughout a semester.

Getting started and what you need

The design is a deliberate choice that lowers the learning curve for the target audience.

The app is free to download, contains ads and offers in-app purchases. The calculators themselves are the product, and the features listed are available across the modes.

Because the app was released in May 2020 and last updated in October 2026, it has had several years of development behind it. The 4.8 rating from over 562,000 ratings suggests that the experience has been positive for a large number of users, though individual needs will vary.

Who will get the most from it

This app is built for students and engineering students, and that focus shows in the mode structure. If you are working through high school algebra, university calculus, linear algebra or physics, the combination of a basic calculator, a scientific calculator, an equation solver, a CAS and a graphing mode covers most of what you will encounter. The breadth means you are less likely to need a second app when a course changes direction.

The keyboard mimicking familiar calculator models is a real advantage for anyone who has used a 991 or 84 plus before. It reduces the friction of moving to a phone or tablet for calculations. For a student who wants one app that can handle fractions in the morning and implicit graphs in the evening, this is a strong candidate.

The free price and the large install base make it easy to try. If you are comfortable with that model and want a wide-ranging calculator suite, the app is worth installing.

A broad calculator suite for students

Scientific calculator plus 991 is a free Android app that packs five calculator modes into one package. It covers basic arithmetic, fractions, trigonometry, logarithms, linear algebra, calculus, complex numbers, matrices, vectors, equation solving, symbolic calculation and graphing.

The app is best suited to students and engineering students who want a single tool for coursework and problem sets. The keyboard layout matching familiar calculator models should make it approachable, and the range of modes means it can grow with you as your courses get harder.

If you need a calculator that handles everything from fractions to implicit graphs, this one is built for exactly that. It is free to try, and the breadth of functions makes it a practical choice for anyone studying math, science or engineering.

What's new in version 7.6.5.7

We appreciate all your valuable feedback. In this update, we added new features, fixed some issues, and improved the math engine. Thank you for using our app.