RightFigures

Math

Standard and scientific calculator

Evaluate one expression. Switch between a standard keypad and scientific functions without leaving the page.

Free to useNo sign-upCalculated in your browser

Expression

Mode

Your expression stays in this browser. History is cleared on reload.

Result

Enter an expression and press equals. An incomplete expression or a domain error stays on screen so you can correct it.

What this calculator evaluates

Type or tap one expression. Standard mode does arithmetic: addition, subtraction, multiplication, division, parentheses, a sign change and percent. Scientific mode adds powers, square roots, sine, cosine, tangent and their inverses, common and natural logs, factorial, π, e and Ans. Switch modes without losing the expression you already typed.

Khan Academy’s order of operations is the binding order used here. Multiplication and division happen before addition and subtraction, and parentheses group first. Powers are right-associative, so 2^3^2 is 2^(3^2) = 512, not (2^3)^2. Unary minus sits outside a power: -3^2 is −9, while (-3)^2 is 9. 2^-3 is 0.125.

Percent

A percent is a number of hundredths, as in Khan Academy’s percentages lesson. On this keypad the trailing % follows one extra rule so a price-style increase works:

  • 200+15% is 200 plus 15% of 200, which is 230. 200-15% is 170.
  • 200×15% is 200 times 0.15, which is 30. 200÷15% divides by 0.15.
  • A percent by itself, such as 50%, is 0.5.
  • The “percent of the left” rule applies only when the right side of + or − is a single value with one %. 200+15%×2 is 200.3, because the percent is part of a product.

Degrees, radians and Ans

Sine, cosine and tangent take degrees until you choose radians. Inverse trig returns that same unit, so asin(0.5) in degrees is 30. The function definitions follow the NIST DLMF trigonometric definitions and the logarithm, exponential and power definitions. log is base 10. ln is natural. sqrt is the non-negative square root. Factorial is the product of whole numbers from 1 through n, and 0! is 1.

Ans is the previous successful result, kept in memory at full binary64 precision rather than the rounded display. After a result, scientific mode continues an operator or sign change from Ans. Standard mode continues from a full-precision decimal of that same value, never from Ans and never from the rounded display. A decimal that cannot fit is left unchanged so the value is not shortened. History keeps the last 20 successful expressions in this tab and disappears on reload. Nothing is saved on the server.

Rounding and errors

Each operation uses IEEE-754 binary64, the ordinary floating-point number available in the browser. The display keeps 12 significant digits, rounding half away from zero, and switches to scientific notation at 1e12 or below 1e-6. 0.1+0.2 displays as 0.3. That display is not a claim of exact decimal arithmetic.

Division by zero, 0^0, a negative number raised to a non-whole power, a factorial outside the whole numbers 0 through 170, a negative square root, a non-positive log, and inverse sine or cosine outside −1 to 1 are rejected. Integer multiples of 90 degrees where tangent is undefined are rejected. In radians, an angle extremely close to an asymptote can still produce a huge finite value. The expression stays so you can backspace and correct it. A result is never clamped to a nearby number.

Example

2+3×4 is 14. (2+3)×4 is 20. sin(30) in degrees is 0.5. 5! is 120.

Frequently asked questions

Why is 200+15% equal to 230 rather than 200.15? The keypad treats a single percent after plus or minus as a percent of the other amount. Use 200+15%×1 or multiply by 0.15 yourself when you want the percent only as a hundredth inside a larger product.

Does standard mode change the expression? No. Switching to standard hides the scientific keys. If the expression still contains a power, root, function, factorial, π, e or Ans, Equals explains that those need scientific mode.

Where does history go? It stays in the page’s memory. Reload clears it. Expressions and results are not written into the address bar, analytics or storage. Repeating the same expression and result, including a mode change that does not change the number, does not add another row. A changed result does.

Sources & review

Last reviewed: . The formula is reproduced above so you can check the math independently.

Educational arithmetic only. Binary64 rounding is not exact decimal arithmetic, and this is not a financial or measurement standard.