What the Scientific Calculator does
This scientific calculator evaluates a whole expression - trigonometry in degrees, radians or gradians, logarithms, powers and roots, factorials, permutations and combinations, the constants pi and e, the previous answer and a memory register - and shows the answer together with exactly how it grouped what you typed. Type on your keyboard or tap the keypad; press = or Enter.
Every answer comes from a small parser written for this page, not from the browser running your text as code. That matters for two reasons: nothing you type can do anything except calculate, and the rules of precedence are fixed and written down below, so you can check the "Read as" line whenever a result surprises you. It all runs in your browser and nothing is sent anywhere.
How to use it
- Choose the angle unit first - Deg for school geometry and most homework, Rad for calculus and physics formulas, Grad if your course uses gradians. The trig functions and their inverses follow this setting.
- Type the expression or tap the keys. Functions open a bracket for you (sin( ), and if you forget to close brackets the calculator closes them at the end. You can write
2pi,3(4+1)orsin30without the multiplication sign. - Watch the grey preview line under the expression: it shows the answer as you type, so you can catch a typo before you press =.
- Press = or Enter. The answer appears large on the right, with the fully bracketed "Read as" version and the unrounded value. Typing an operator straight afterwards continues from the answer (Ans); typing a digit starts a new calculation.
- Use M+ and M- to keep a running total, MR to put it back into an expression and MC to clear it. Every result also goes into the history table, where Use drops it back into the expression; copy the history or download it as CSV.
Reading the results
The big number is rounded to 12 significant figures; the "Full precision" line shows the stored double-precision value. They differ only in the last few digits, which is where binary floating point cannot represent decimals such as 0.1 exactly.
The "Read as" line is the most useful check on a calculator. If you typed -3^2 and expected 9, it shows −(3^2), which tells you to write (-3)^2. If you typed 1/2pi meaning one over two pi, it shows (1 ÷ 2) × π and you know to add brackets.
An error message means the calculator refused rather than guessed: tan of 90 degrees, the square root of a negative number, log of zero and 0 to a negative power have no real answer, and two numbers side by side with nothing between them are ambiguous.
Worked example: the height of a ramp and a tricky power
A 4 m ramp rises at 30 degrees. In Deg mode, 4sin(30) is read as 4 × sin(30); sin 30° is exactly one half, so the ramp rises 2 m. In Rad mode the same keys give 4 × sin(30 radians) = -3.952..., which is why the angle unit is the first thing to check.
1000(1+0.05)^10 is the value of 1,000 after ten years at 5% compounded yearly. The power is applied before the implicit multiplication: 1.05^10 = 1.62889462678, so the answer is 1,628.89462678.
2^3^2 is 512, not 64. Powers are evaluated right to left, as in algebra: 3^2 = 9 first, then 2^9 = 512. The "Read as" line shows 2^(3^2).
52 nCr 5 counts five-card hands from a 52-card deck: 52 × 51 × 50 × 49 × 48 / 5! = 311,875,200 / 120 = 2,598,960.
Formulas and scoring rules
- Order of operations
( ) > postfix ! % > ^ (right to left) > unary minus > nPr nCr > × ÷ and implicit × (left to right) > + − (left to right)So -2^2 = -4, 2^3^2 = 512 and 2 × 5 nCr 2 = 20.- Angle conversion
radians = degrees × π / 180 = gradians × π / 200At exact multiples of a right angle sin, cos and tan return exact values (sin 180° = 0, tan 90° undefined) instead of a tiny rounding residue.- Permutations and combinations
nPr = n! / (n − r)! nCr = n! / (r! (n − r)!)Computed by multiplying r terms, so 1000 nCr 2 works without forming 1000!.- Factorial of a non-integer
x! = Γ(x + 1)Gamma by the Lanczos approximation, accurate to about 15 significant digits: 0.5! = √π / 2 = 0.886226925453.- Percent
x% = x / 100; a + b% = a × (1 + b/100); a − b% = a × (1 − b/100)- Logarithms
log x = log10 x; ln x = log_e x; log(x, b) = ln x / ln b- Display rounding
12 significant figures; E form at 10^15 and above or below 10^-9Double precision carries about 15-17 significant digits; the last few are not trustworthy after a long chain of operations.
Why calculators disagree about -2^2 and 1/2x
There is no international standard for how a calculator parses a line of text, and real calculators differ. Algebra writes -x² to mean -(x²), and this calculator follows that, as do most spreadsheet-free computer algebra systems; some spreadsheets treat the minus as part of the number and give +4. Likewise some handheld models give implicit multiplication a higher priority than division, so 1/2π becomes 1/(2π). Here it has the same priority as ×, which is what the written rule says.
The safe habit is the same everywhere: when an expression mixes a leading minus with a power, or a division with an implied product, add brackets. The Read as line removes the guesswork for this page.
Why 0.1 + 0.2 is not exactly 0.3 inside a computer
Computers store numbers in binary, and one tenth has no finite binary expansion, just as one third has no finite decimal one. The nearest double-precision values to 0.1 and 0.2 add up to 0.30000000000000004. Showing 12 significant figures hides that last-place residue without changing the arithmetic, which is what handheld scientific calculators do with their 10-digit displays and guard digits.
Limitations: what the result does not prove
- It works with real numbers only. Square roots of negatives, logs of negatives and similar complex results are refused with an explanation rather than returned as imaginary numbers.
- Accuracy is that of IEEE 754 double precision - about 15 significant digits. Subtracting two nearly equal large numbers, or very large factorials, can lose digits; the full-precision line shows what is actually stored.
- It is not a graphing, matrix, statistics or equation-solving calculator. Use the quadratic equation solver for roots of polynomials and the standard deviation calculator for data sets.
- Exam rules usually require an approved physical calculator. Check your exam board's list before relying on any online calculator for assessed work.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- IEEE 754-2019 - Standard for Floating-Point Arithmetic
- NIST Digital Library of Mathematical Functions - Gamma function (5.2)
- NIST SP 811 - Guide for the Use of the International System of Units (angles, radians)
Frequently asked questions
How do I switch between degrees and radians?
Use the Deg, Rad and Grad buttons above the screen before you calculate. The setting changes sin, cos and tan and the inverse functions. You can also override one value by typing a unit, as in sin(90deg) while in Rad mode.
Why does -2^2 give -4 on this calculator?
Because a leading minus is applied after the power, the way algebra writes -x². The calculator reads it as −(2^2). Type (-2)^2 if you want the square of minus two, which is 4.
What does 2^3^2 equal and why?
512. Powers stack from the right, so 3^2 = 9 is worked out first and then 2^9 = 512. Bracket the left part, (2^3)^2, if you want 8^2 = 64.
How do I calculate nCr and nPr?
Type them between the two numbers, such as 10 nCr 3 (120) or 10 nPr 3 (720), or tap the nCr and nPr keys. The function forms nCr(10,3) and nPr(10,3) work too. Both need whole numbers with r no larger than n.
Can I take the factorial of a decimal number?
Yes. For non-integers the calculator uses the gamma function, x! = Γ(x+1), so 0.5! = 0.886226925453 (half the square root of pi). Negative whole numbers have no factorial and are refused.
How does the percent key work in 200 + 10%?
Directly after + or − a percentage is taken of the left-hand side, the way phone and desk calculators behave, so 200 + 10% = 220 and 200 − 25% = 150. Anywhere else x% simply means x divided by 100, so 200 × 10% = 20.
Does this online calculator work with my keyboard?
Yes. Type digits, operators, brackets, ^ and ! directly; Enter or = calculates, Escape clears and Backspace deletes. When focus is on a keypad button the same keys still go into the expression.
Is my calculation history saved or sent anywhere?
No. History, memory and Ans live only in this browser tab and disappear when you close or reload it. Nothing is sent to a server; download the history as CSV if you want to keep it.
Last reviewed by the A2Z.Tools team against the sources listed above.
