Slide RuleENGINEERING & SCIENCE TOOLKIT Open the app ↗
TOOL 01 / CALCULATOR

A scientific calculator that shows its working.

Type a calculation the way you would write it on paper. Get an exact answer, then open the steps and see which rule was used at each one.

Open the calculator — Free ↗What it does ↓

No account required · Right in your browser · Works offline once opened

SLIDE RULE / CalculatorSCREENSHOT
The Slide Rule calculator solving x squared plus 6 equals 5x, with the working panel beside it showing each step of factorising the quadratic
Solving a quadratic. The working names each step: move everything to one side, factorise, set each bracket to zero, check.
WHAT IT DOES

More than the calculator in your pencil case.

It does the arithmetic of a scientific calculator and the algebra and calculus of a symbolic one, and it can explain itself.

Laid out as you would write it

Fractions, powers, roots and brackets are drawn as mathematics while you type. Click any part of the expression to change it, including an exponent or the index of a root.

Working for each answer

Press Show working and the steps open beside the calculation, each naming the rule it used: the product rule, integration by parts, L’Hôpital’s rule, factorising a quadratic.

Calculus

Derivatives and partial derivatives, antiderivatives, definite integrals, limits and Taylor series. With letters you get the formula; with numbers, the value.

Algebra

Solve an equation for any letter in it, simplify, expand brackets and factorise polynomials. A letter with no stored value stays a letter, so 2x + 3x gives 5x.

Exact when it can be

A calculation typed without decimals keeps an exact answer, shown as a fraction. Choose decimal, scientific or engineering notation, 4 to 15 digits, and degrees or radians.

Units, complex numbers, uncertainty

Convert inline with 200 GPa to ksi. Enter a phasor as 5∠30 and see the polar form of every complex answer. Type 2.31 ± 0.02 and the ± is carried through the calculation.

TRY THESE

What goes in, what comes out.

Each of these is an answer the calculator gives. The ones marked with a method have their steps under Show working.

  • YOU ENTERSLIDE RULE ANSWERSWHAT HAPPENED
  • x² + 6 = 5xx = 2 or x = 3Solved by factorising, with a check of each answer in the original equation.
  • d/dx x² sin xx² cos x + 2x sin xThe product rule.
  • ∫ x eˣ dxeˣ(x − 1) + CIntegration by parts, then checked by differentiating.
  • ∫₀³ x² dx9A definite integral with an exact value.
  • lim x→0 sin x / x1Putting the value in gives 0/0, so L’Hôpital’s rule is used.
  • (3 + 4i)(1 − 2i)11 − 2iThe polar form, 11.18 ∠ −10.3°, is shown underneath.
  • 1/3 + 1/47/12An exact fraction, because nothing was typed as a decimal.
  • factor x³ − 8(x − 2)(x² + 2x + 4)A polynomial factorised.
  • 200 GPa to ksi29007.54755 ksiA unit conversion, typed straight into the calculator.
KEYBOARD OR KEYS

Quick to type, on a laptop or a phone.

Every function has a key on screen, grouped as calculus, algebra, complex numbers and scientific. With a keyboard you rarely need them.

Store a value with r = 0.25 and use it anywhere, as in pi r^2. Define your own function with f(x) = x^2 + 1. Earlier calculations stay in the history: click one to bring it back, or its answer to reuse the result.

WHILE TYPING

  • /makes a fraction
  • ^starts a power
  • _a subscript
  • sqrt(a root
  • Enterevaluates
  • ↑ ↓earlier calculations
  • Escclears the entry

ANYWHERE IN THE APP

  • /search everything
  • Alt + 1 … 8switch tool
QUESTIONS

Before you open it.

Is the calculator free?

Yes. The calculator and its step-by-step working are part of the free plan, and you do not need an account to use them.

Does it work offline?

Yes. Open the app once while you are online and it keeps working without a connection. You can also install it from your browser’s menu.

Degrees or radians?

Either: there is a DEG / RAD switch beside the entry. Derivatives and integrals of trigonometric functions always use radians, and the calculator says so when it matters.

Can I keep my working?

Send any calculation to a worksheet with Add to worksheet, where it sits beside your notes and other results. Signing in saves your history and stored values to your account.

One of eight tools that work together.

A value from one goes straight into another
NOTHING TO INSTALL

Try it on your next problem.

Open the calculator — Free ↗

No account required. Free for every tool; Pro adds unlimited worksheets and exports.