百分比计算器

How this calculator reads what you type

Unlike a basic calculator that computes the moment you press an operator, this scientific calculator builds up an entire expression string as you tap buttons, then evaluates it all at once when you press =. That design is what lets you write something like sin(45 + 45) or √(9 + 16) and get the right answer: the calculator respects standard operator precedence and the contents of parentheses, evaluating the inner sum first. A simpler tool would multiply or take a function of only the first number and discard the rest.

When you press equals, the on-screen symbols are translated to their mathematical meanings — × becomes multiplication, ÷ division, π becomes 3.14159…, e becomes 2.71828…, and mod becomes the remainder operator — and the full expression is computed. The result is rounded to about ten decimal places to hide floating-point noise, and very long results switch to scientific notation so they stay readable.

Degrees versus radians: the setting that trips everyone up

The single most common source of "wrong" trigonometry answers is the angle mode. Tap the DEG / RAD indicator to switch. In DEG mode the calculator interprets sin(30) as 30 degrees, giving exactly 0.5. In RAD mode the same sin(30) treats 30 as radians — roughly 4.77 full circles — and returns about −0.988. Internally, degree inputs are converted to radians (multiply by π/180) before the trig function runs, because the underlying math library works in radians. Always glance at the mode indicator before trusting a trig result.

What each function family computes

A practical caveat: log here is base 10, not base 2 or natural log. If you need a natural log use ln. Factorial is rounded to a whole number and capped at 170 because 171! exceeds the largest number JavaScript can represent, so anything above that returns an error rather than a meaningless infinity.

A worked example: chaining a calculation

Suppose you want the hypotenuse of a right triangle with legs 3 and 4. In DEG mode (the mode is irrelevant here since there is no trig) type √(3 x² + 4 x²). The calculator turns this into the square root of 9 + 16 = 25 and returns 5. Now press M+ to add 5 to memory. Start a new calculation, and at any point press MR to recall that stored 5, or use ANS-style chaining: after pressing equals, the result becomes the starting value of your next expression, so you can keep building on it. MC clears memory and M− subtracts the current value from it.

Memory keys and history

The memory register persists across calculations until you clear it, which is handy when you need to set aside a running subtotal — for example, summing several intermediate results that each require their own expression. Every completed calculation is also written to a scrollable history list (the most recent twenty), showing both the expression and its answer, so you can verify a step or copy a previous result.

Tips and common mistakes

• Balance your parentheses. Function buttons like sin( and √( open a parenthesis for you; remember to close it. An unbalanced expression evaluates to "Error" rather than guessing your intent.
• Mind the angle mode for inverse problems too. If you compute an angle and the number looks like radians when you expected degrees, you left the calculator in RAD.
• Use keyboard input. Digits, ., (), %, the four operators, and Enter/Escape all work from your keyboard, which is far faster than clicking for long expressions.
• Factorials grow explosively. Even 20! is over two quintillion; the 170 cap is a hard mathematical limit, not an arbitrary restriction.

Privacy

The calculator evaluates everything locally in your browser — no expression or result is sent to a server. It works offline, and nothing you compute is logged or stored beyond the on-page history, which disappears when you close the tab.