How the Windows-style calculator works

This calculator is styled after the one in Microsoft Windows and runs entirely in your browser: nothing you type is sent to a server. Use the standard mode for everyday sums, percentages, square roots and reciprocals, and switch to the scientific mode for trigonometry, logarithms, powers, factorials and constants. You can click the keys, or type on the keyboard after clicking the calculator: digits, the decimal point, + - * /, Enter or = for the result, Backspace to delete a digit, Delete to clear the entry (CE) and Escape to clear everything (C).

Operations run as you type, from left to right, like the Windows standard mode: when you press a second operator, the pending operation is calculated first, so 2 + 3 × 4 gives 20, not 14. The % key divides the displayed number by 100. The memory keys hold a single number: MS stores the display, MR recalls it, M+ and M− add or subtract the display and MC clears it. The scientific mode adds trigonometric and hyperbolic functions, logarithms, powers, roots, n!, mod, π and e; the 2nd key switches to the inverse functions and the angle button cycles through degrees, radians and gradians.

Example: in degree mode, type 30 and press sin to get 0.5; type 5 and press n! to get 120; type 2, press xʸ, type 10 and press = to get 1024. Limitations: calculations use standard double-precision floating-point numbers, so the display is rounded to 10 decimal places and very large or very small results switch to exponential notation (F-E forces it); factorials accept only whole numbers from 0 to 170; invalid operations, such as dividing by zero, show Error. There are no parentheses keys and no history, so split long formulas into steps.