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Scientific Calculator

Online scientific calculator with trig, logs, roots and powers.

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How to use

  1. Click the on-screen keys, or type directly: digits 0–9, decimal point, + − × ÷ (as * /), ^, parentheses, Enter to evaluate (=), Backspace to delete one character, Esc to clear.
  2. Trigonometry defaults to degrees (DEG): type 30 then press sin to get 0.5. Switch to radians with the "DEG / RAD" key, and open results are recalculated immediately.
  3. sin / cos / tan / ln / log / |x| / √ first act on the number on screen; when there is no number they insert a function prefix so you can build expressions such as sin(30+5) or √(9) with parentheses. x², 1/x and x! always act on the current number: enter a number first.
  4. Calculations follow mathematical precedence: powers first, then multiplication/division, then addition/subtraction; parentheses override the order. Pressing a second operator replaces the first one, and values next to π, e or ( get an implicit multiplication sign.
  5. Results keep up to about 10 significant digits and floating-point noise is trimmed automatically (0.1 + 0.2 shows 0.3). Invalid operations such as division by zero or the square root of a negative number show an error: press C or Esc to start over.

FAQ

Are trigonometric functions in degrees or radians?
The default is degrees (DEG), where sin(30) = 0.5 and cos(60) = 0.5. Pressing the DEG key on the keypad switches to radians: the key then reads RAD, and sin(30) is about −0.988 in radians. Open trig results are recalculated instantly when you switch modes.
How do I type with the keyboard?
Type digits, the decimal point and the keys + − * / ^ ( ). Press Enter or = to evaluate, Backspace to delete one character, and Esc to clear everything (same as the C key). If focus is inside an input or another control on the page, click the calculator area first.
Why doesn't 0.1 + 0.2 show 0.30000000000000004?
Computers store decimals as binary floating point, so 0.1 + 0.2 is internally a very long approximation. This calculator trims the result to about 10 significant digits and removes the noise tail on display, so you simply see 0.3.
What happens with division by zero or the square root of a negative number?
Dividing by zero, taking the square root of a negative number, the logarithm of a non-positive number, the reciprocal of 0, or a factorial outside 0–170 (non-negative integers only) shows an error and no result. Press C or Esc to reset. Results beyond about 1e308 are reported as too large.

How to use

  1. Know the display and keypad

    The display has two lines: a small expression line and a large current-value line. Below, the keypad mixes digits and operators with a scientific function block on top.

  2. Type with the keyboard

    Digits, the decimal point, + - * /, ^ and parentheses all work from the keyboard. Enter evaluates, Backspace deletes one character and Esc clears like C.

  3. Switch DEG and RAD

    Trigonometry starts in degrees: type 30 then sin to get 0.5. Press the DEG key to flip to radians, and trig results already on screen recalculate instantly.

  4. Combine the function keys

    sin, cos, tan, ln, log, √ and |x| act on the number on screen. With no number they insert a prefix, so you can write sin(30+5). x², 1/x and x! act on the current number.

  5. Recover from errors

    Division by zero, square roots of negatives and similar invalid operations show an error instead of a number. Press C or Esc and start the expression over.

About this tool

This scientific calculator covers arithmetic plus sin/cos/tan, the natural and common logarithms ln and log, square roots and powers via x^y. It also handles reciprocals, absolute values and factorials, and carries the constants π and e. Evaluation follows standard precedence: powers first, then multiplication and division, then addition and subtraction. Parentheses override it. Values next to π, e or an opening parenthesis get an implicit multiplication sign.

It suits homework checks, quick engineering estimates and everyday lookups. The display trims binary floating-point noise, so 0.1 + 0.2 shows a clean 0.3, and results keep about 10 significant digits. Trigonometry defaults to degrees. After switching to radians with the DEG key, trig values already on screen are recomputed at once. Factorials accept non-negative integers up to 170, and invalid operations report errors clearly.

How it works

Most calculator surprises trace back to IEEE 754 double precision. Of the 64 bits, one holds the sign, eleven the exponent and fifty-two the mantissa. Values like 0.1 and 0.2 have no exact binary form, so their sum is genuinely 0.30000000000000004. The display trims that noise to a clean 0.3. Trimming has limits. Integers past 1e16 lose their tail silently, and beyond the double maximum near 1.8×10^308 the screen shows Infinity. The factorial key stops at 170 against the same wall: 170! still fits, while 171! overflows. Exact integer accounting belongs to big-number libraries, not to any floating-point calculator.

The DEG/RAD distinction comes from the radian itself. One radian is the angle whose arc equals the radius, and a full turn is 2π radians or 360°. The conversion factor is 180/π ≈ 57.2958. Radians make calculus work: the derivative of sin is cos, and the small-angle approximation sin x ≈ x holds. That is why physics defaults to them. Mental arithmetic prefers degrees, so the tool starts in DEG and flips on demand. Evaluation runs powers first, then multiplication and division, then addition and subtraction, with equal-precedence operators going left to right. A value sitting next to π, e or an opening parenthesis receives an implicit multiplication sign. When in doubt, group with parentheses.

When to use it

  1. Checking homework

    Type the expression exactly as written, press Enter and compare. Standard values like sin 30 = 0.5 in DEG mode separate a formula written wrong from a number computed wrong within seconds.

  2. Fast field estimates

    Combine x^y and √ for rough engineering. The area of a 30-unit circle is π×15², and slope, decay or conversion formulas each fit on one line. Ten significant digits far exceed what an estimate needs.

  3. Explaining float output

    Reproduce classics such as 0.1+0.2 or 1/3×3 here and compare with the trimmed on-screen result. Then explain what Python or JavaScript actually printed, and debugging a float display stops feeling like witchcraft.

Tips & tricks

  • Enter the number first, then press sin or log. That is faster than wrapping everything in parentheses.
  • Cube roots: type x^(1÷3). Use the ± key to flip a value negative instead of retyping it.
  • Keyboard input stops working while focus is in another page input. Click the calculator area first.

Things to watch

  • Undefined operations error out

    Division by zero, the reciprocal of zero and square roots of negatives have no real answer. The display shows an error instead of a number. Complex results like the square root of -4 remain out of scope.

  • Precision caps near 16 digits

    A double carries roughly 15-16 significant digits, and integer tails above 1e16 are unreliable. Exact arithmetic on thousand-digit numbers belongs to big-integer libraries, not to any floating-point calculator.

  • Precedence and the minus sign

    Powers bind before multiplication and division, and -3² is the negative of (-3)². Equal-precedence operators run left to right, so 8÷4×2 is 4, not 1. When in doubt, spend two keystrokes on parentheses.

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