Soulver!

Wolfram Alpha is a "Computational Knowledge Engine" - different from a search engine, it answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer.

SpeedCrunch is a free, fast, high precision open source algebraic calculator with an intuitive interface and a extensive list of features, including: Unlimited Variables, Syntax Highlighting, Functions, with 'Automagic' Completion, 50 Decimal Precision, Input History and more...

Mathematica is a computational software program used widely in scientific, engineering, and mathematical fields and other areas of technical computing.

Qalculate! is a multi-purpose desktop calculator for GNU/Linux and Windows. It is small and simple to use but with much power and versatility underneath. Features include customizable functions, units, arbitrary precision, plotting, and a user-friendly interface (KDE or GTK+).

Numi is a handy calculator app for Mac. It allows to describe tasks the natural way and instantly get an accurate answer. For example, $20 in euro - 5% discount or today + 2 weeks. Numi is not limited to simple calculations, it can solve expressions of any complexity, with parentheses, mathematical operations and high accuracy (up to 38 mantissa digits).

OpalCalc is a brand new type of calculator for the PC. As easy to use as Notepad or a word processor, OpalCalc allows natural language in the sum and multi-line support so you can go back and adjust your previous calculations on the fly.

Its an app where you do maths like a normal person. It lets you type whatever you want and smartly figures out what is math and spits out an answer on the right pane. Then you can plug those answers in to future equations and if that answer changes, so does the equations its used in.

Online math solver, equation library, graphing calculator and science/engineering problem helper.Calculate multiple equations at once, Edit existing formulas and Create new ones, Compute large numbers of values, Plot graphs, Link your results, Solve full problems and Share worksheets with your friends.

RealCalc Scientific CalculatorAndroid's #1 Scientific Calculator. A fully featured scientific calculator which looks and operates like the real thing.Looking for fractions? Degrees/minutes/seconds? Landscape mode? You need RealCalc Plus. See elsewhere on this page for the link, or select 'Upgrade' from the RealCalc menu.RealCalc includes the following features:* Traditional algebraic or RPN operation* Result history* Unit conversions* Physical constants table* Percentages* 10 memories* Binary, octal, and hexadecimal* Trig functions in degrees, radians or grads* Scientific, engineering and fixed-point display modes* Configurable digit grouping and decimal point* Full built-in help* A complete lack of advertisingRealCalc Plus contains all these features, plus:* Fraction calculations and conversion to/from decimal* Degrees/minutes/seconds calculations and conversion* Landscape mode* User-customizable unit conversions* User-customizable constantsIf you find RealCalc useful, please consider purchasing RealCalc Plus to support further development. Thank you.FAQ:* If you want data size conversions in multiples of 1024, use kibibytes, mebibytes, gibibytes, etc - see en.wikipedia.org/wiki/Kibibyte.* If the percent key appears to give wrong answers, make sure you are pressing '=' at the end, e.g. '25 + 10 % =' will give 27.5.* If sin/cos/tan functions don't give the answer you are expecting, make sure you are in the correct angle mode. Degrees, radians and grads are supported, indicated by DEG, RAD, GRAD in the display. Use the DRG key to change mode.* If any of the digit keys are disabled, or the decimal point doesn't work, or you have answers with letters in, or basic arithmetic appears to be wrong, then you are in binary, octal or hexadecimal mode. Press DEC to return to decimal operation. If you don't need these modes, please make sure that 'Enable Radix Modes' is disabled in the settings.Please read the help for more information. »

Calca is a powerful symbolic calculator that updates as you type giving you instant answers. It solves equations and simplifies complex expressions. It's also a rich Markdown text editor so that you can explain your ideas alongside your calculations.

Windows Calculator, commonly known as Calculator from the application's title bar, is a calculation application included in all versions of the Microsoft Windows operating system. It can be activated by the command "calc" on most Windows systems.

CalcTape is a revolutionary new kind of pocket calculator. With CalcTape, also extensive calculations remain clearly structured. CalcTape makes the arithmetic process visible - you can generate intermediate results and subsequently correct or change all numbers and operations.

With MyScript Calculator, perform mathematical operations naturally using your handwriting.

Calcbot is a simple and beautifully designed calculator for your iPhone, iPod touch and iPad. You’ll never open the built-in Calculator app again.