Scientific Calculator

Features

Light, super fast and it works offline.
Memorizes not only the display if turned off/on but also all other states. It's even possible to continue a calculation sequence after turning computer off/on.
Full Keyboard support: See "Keyboard Support" section below.
Copy/Paste from/to display with Ctrl+C (double click to copy as well) and Ctrl+V.
Dynamic font-size in display to keep numbers as readable as possible.
Real sci-calc-style calculations, so 1+2*3=7 (... not 9 like with others),
and 1*(2+3)=5=25 (... not 8 like with other calculators).
You can theoretically use an unlimited amount of parentheses.
No need to close parentheses if equation sign follows anyhow.

Using the Calculator

Click on numbers and functions in Calculator just as you would with a standard calculator.
When you click the add, subtract, multiply, or divide button (in scientific mode also: y^x, ^x√y, EE and the opened parenthesis), a white shadow appears around the button to let you know the operation to be carried out. The white shadow around the opened parenthesis will stay until all parentheses expressions are closed.

This calculator uses an algebraic method of entry that allows you to enter mathematical sequences in the same order that they are algebraically stated (PEMDAS / AOS™).
PEMDAS: "Parentheses, Exponents, Multiplication or Division, and Addition or Subtraction". Multiplication and division have the same ranking. Addition and subtraction as well.

Keyboard Support

There is full keyboard support for each button on the calculator.

The numbers and + – × ÷ , . = keys can also be input on number block.
See below the keyboard shortcuts of each calculator button in [brackets].
Use the [Backspace] key to correct the last, single input number, point or +/- sign.
Hold key: [h, s] means: press h or H and you'll see a little 'hold' in the right bottom corner of the display.
This makes the followed key function different: [s] = sin, but [h, s] = sinh, etc.
Copy/Paste from/to display with Ctrl+C and Ctrl+V.
All [ENTER] keys represent the '=' button.

Standard Functions

[Del or Shift+Backspace] Click to clear the displayed number. Removes an incorrect entry/number from the display when pressed before any function or operation key is pressed.

[Del or Shift+Backspace] Click to clear the displayed number and the constant and pending operations.

[ENTER] Finishes any function or operation and displays the result.
If there are any unfinished parentheses expressions before this key is clicked or hit,
they get finished automaticaly. 2*(2+3*(2+4))=40 is the same as typing 2*(2+3*(2+4=40.

[*] Multiplys the value.

[/] Divides the value.

[+] Adds the value.

–

[-] Subtracts the value.

+/–

[#] Changes the algebraic sign.

Scientific Functions

2nd

[Space] Changes the trigonometric buttons (sin, cos, tan, sinh, cosh, and tanh)
to their inverse functions (sin^-1, cos^-1, tan^-1, sinh^-1, cosh^-1, and tanh^-1). It also changes ln to log₂, and e^x to 2^x. Click 2nd again to return the buttons to their original functions.

(

[(] Opens a parenthetical expression. Expressions can be nested. Clicking on it lets a white ring appear around the button to let you know that a parenthetical expresion is still active (until all expressions are closed with the closeing parenthesis or the equation sign).

)

[)] Closes a parenthetical expression. The white ring around the ( parenthesis key will stay until all expressions are closed with this key or after clicking the equation sign.

[%] Calculates percentages, adds markups, and subtracts discounts. To calculate a percentage, use it with the +, –, × or ÷ keys. For example, to calculate 8% of 500, enter 500 x 8 % (no equation key (=)) which returns 40. To add a markup or subtract a discount, additionaly use the equation (=) key. For example, to compute the total cost of a $500 item with an 8% sales tax, enter 500 + 8 % = which returns 540.

1/x

[\ or h, 1] Returns the reciprocal of a value in decimal format.

x²

[h, 2] Squares a value.

x³

[h, 3] Cubes a value.

y^x

[^ or ' or "] Click between values to raise the first value to the power of the second value.
For example, to compute 3⁴, enter 3 y^x 4 = which returns 81.

[x] Calculates the factorial of a value (only integers).

√

[h, r] Calculates the square root of a value.

^x√y

[r] Use between values to calculate the x root of y. For example to compute ⁴√81,
enter 81 ^x√y 4 = which returns 3.

log

[Shift+L] Returns the log base 10 of a value.

sin

[s] Calculates the sine of a value.

sin^-1

[Shift+S] Calculates the arc sine of a value. (Available when the 2nd button is clicked).

cos

[c] Calculates the cosine of a value.

cos^-1

[Shift+C] Calculates the arc cosine of a value. (Available when the 2nd button is clicked).

tan

[t] Calculates the tangent of a value.

tan^-1

[Shift+T] Calculates the arc tangent of a value. (Available when the 2nd button is clicked).

[l] Calculates the natural log of a value.

log₂

[h, l] Calculates the log base 2. (Available when the 2nd button is clicked).

sinh

[h, s] Calculates the hyperbolic sine of a value.

sinh ^-1

[h, Shift+S] Calculates the inverse hyperbolic sine of a value. (Available when the 2nd button is clicked).

cosh

[h, c] Calculates the hyperbolic cosine of a value.

cosh^-1

[h, Shift+C] Calculates the inverse hyperbolic cosine of a value. (Available when the 2nd button is clicked).

tanh

[h, t] Calculates the hyperbolic tangent of a value.

tanh^-1

[h, Shift+T] Calculates the inverse hyperbolic tangent of a value. (Available when the 2nd button is clicked).

e^x

[e] Click after entering a value to raise the constant 'e' (2.718281828459045…) to the power of that value.

2^x

[Shift+X or h, e] Calculates 2 to the power of the displayed value. For example, 10 2^x = 1024. (Available when the 2nd button is clicked).

[p] Enters the value of PI or π (3.141592653589793…).

[Shift+E] An operator that multiplies the currently displayed value by 10 to the power of the next value you enter.

Rand

[h, n or h, d] Returns a random number between 0 and 1.

[v] Click to clear the memory.

[b] Click to add the displayed number to the number in memory. If no number is in memory, click to store the displayed number in memory.

[n] Click to subtract the displayed number from the number in memory. If no number is in memory, click to store the displayed number as a subtraction of zero in memory.

[m] Click to replace the displayed number with the number in memory.
If the button has a white ring around it, there is a number stored in memory. The white ring around the button also disappears if the stored number calculates zero.

Deg

[d or °] Changes the mode to express trigonometric functions in degrees.

Rad

[d or °] Changes the mode to express trigonometric functions in radians.

About Precision

This calculator operates with a precision of 15 digits (only) after the decimal point. This is due to how JavaScript handles floating point numbers.
This isn't actually a Javascript feature but a feature of the way the IEEE define how floating point numbers are stored in memory. Any language using this definition suffers from this 'feature', for instance C does as well and since JavaScript is often implemented in C so does JavaScript.

The problem is that Javascript is using 32 bits of data which have 4294967296 different combinations to hold any value in the range 1.7976931348623158e+308 to 2.2250738585072014e–308.
It does this by using a smaller presision value and using some of the bits as a exponent (this can also be done in 16 bits with a smaller range and less presision) which results in it being able to approximate any value in the range but not exactly represent them all (because in real number terms the are an infinaite number of values between any 2 given values).
As part of your calculcation clearly the internal representation of the value is going outside the available presision and you are ending up with an approximation to the value instead of an exact value.