Calculator
Type a whole expression and it is evaluated by precedence, with scientific functions and a history alongside.
An old pocket calculator answers 20 to 2+3×4, because it folds the running total on every key. On paper the answer is 14. Here the whole expression is read and evaluated by precedence, so what you see and what it answers are the same thing — and because the expression stays on screen, you can find the wrong character and fix it.
Expression
What you enter is saved in this browser, so it is still here next time
Type it straight in. Enter calculates, Esc clears.
Result
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History
Pressing = adds to this list. It stays in this browser.
The whole expression is read and evaluated by precedence, not folded as you press keys. 2+3×4 is 14 — the place where an old pocket calculator answers 20.
What % means depends on where it sits — 200+10% is 220 (ten percent of the left side added), while 200×10% is 20 (a plain 0.1). This follows the long-standing calculator convention.
Six levels of precedence
Parentheses and functions come first, then postfix marks such as !, ², ³ and %, then ^, then the sign, then multiplication and division, and last addition and subtraction. So -2^2 is −4, and 2^3^2 groups from the right to give 2⁹ = 512. The multiplication sign is optional: 2(3+4) is 14. 5! is 120, and from 171! it shows as ∞.
Trigonometry defaults to degrees
sin(30) is 0.5 in degree mode and −0.988 in radians. asin(1) comes back as 90 in degree mode. log is base 10, so log(1000) is 3; the natural log is ln. Rounding is round, floor and ceil, with round(2.5) giving 3.
Folded at twelve digits, and very large numbers go exponential
The answer is folded to twelve significant digits and shown to ten decimal places. Anything at or above 10¹⁵ or below 10⁻⁹ in size appears in exponent form, like 7.25741562e+306. Dividing by zero gives ∞. After calculating, the answer takes the place of the expression so you can keep going, and expression and answer are stacked in the history.
What this screen does not do
There are no variables and no equals sign — an assignment like x=3 is a syntax error. Unit conversion, number bases and fractions belong to other tools. A function name must be followed by parentheses, so sin 30 is not accepted. The expression, mode, angle unit and history stay in this browser.
Common questions
QWhat is 200 + 10%?
220. In an addition or subtraction, % means a percentage of the value on the left. In a multiplication or division it is a plain hundredth, so 200 × 10% is 20, and a lone 50% is 0.5. This is the long-standing calculator convention and the answer most people expect.
QDoes 0.1 + 0.2 come out as 0.3?
It does. Because computers hold decimals in binary the arithmetic really produces 0.30000000000000004, but the residue only appears below the twelfth digit. The display folds at twelve significant digits, which removes the residue and leaves the real value intact.
QCan I use the keyboard?
Yes. The expression is an ordinary text field, so digits and operators type straight in. Enter calculates and Esc clears. Both * and ×, and / and ÷, are understood, and an amount pasted with thousands separators like 1,234,567 is read as one number.
QWhy is 1e3 not 1,000?
Because e is read as Euler's number, 2.718…. A letter next to a digit is taken as an omitted multiplication sign, so 1 × e × 3 = 8.1548454854. For a thousand, type 1000 or 10^3.
QHow many history entries are kept?
Twenty. New calculations stack on top, and from the twenty-first the oldest line drops off. Pressing a line brings that expression back into the field, and nothing is sent to a server.