Basic Calculator
A simple four-function calculator with a clickable keypad for everyday arithmetic.
Example
Compute 12 + 8 then take 50%:
Press: 1 2 + 8 = shows 20
Press: 5 0 % shows 10 (50% of 20)
How it works
Tap the digit and operator keys to enter a calculation, then press = to see the result. Use C to clear, +/- to flip the sign, and % to convert to a percentage.
Good to know
The Basic Calculator is a four-function arithmetic tool with a clickable on-screen keypad for addition, subtraction, multiplication, and division, plus a percent key, a sign toggle (+/-), a decimal point, and a clear button. It is built for quick everyday math, splitting a bill, checking a discount, adding up a few numbers, where you want a tactile calculator in the browser without opening a spreadsheet or trusting a search box.
Reach for it when you have a short chain of operations rather than a single formula. You enter a number, choose an operator, enter the next number, and either press another operator to continue or press = to finish. Because it evaluates each operator immediately (left to right), it does not apply standard order of operations: typing 2 + 3 × 4 gives 20, not 14, because the + is settled before the × is applied. For mixed multiplication and addition where precedence matters, compute the multiplication part first and reuse the result.
The result is shown right-aligned and rounded to 12 significant digits, so very long or repeating decimals are trimmed rather than displayed in full. A reading of "Error" means an undefined operation occurred, most commonly division by zero; press C to reset before continuing. Negative zero is normalized to plain 0 so you never see a confusing "-0" on screen.
A practical caveat: the percent key is context-sensitive. With a pending operation it works relative to the first number (200 + 10% adds 10% of 200), but with nothing pending it simply divides the shown value by 100. Everything runs locally in your browser, so nothing you type is uploaded, but there is no calculation history or memory function, jot down intermediate results if you need them later.
Frequently asked questions
How does the % key work?
With a pending operation, % treats the current number as a percentage of the first operand (e.g. 200 + 10% gives 220). With no pending operation it simply divides the displayed number by 100.
What happens when I divide by zero?
The display shows "Error" instead of Infinity or NaN. Press C to clear and start a new calculation.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser; nothing is uploaded.
Is it free?
Yes, completely free with no sign-up and no limits.
People also ask
Does the basic calculator follow order of operations (PEMDAS)?
No. It evaluates operators immediately in the order you enter them, left to right, so 2 + 3 × 4 returns 20 rather than 14. To respect precedence, calculate the multiplication or division portion first and then add or subtract.
How do I calculate a percentage discount with this calculator?
To take 20% off a 50 price, enter 50, press the minus operator, type 20, then press %. The percent key applies 20% of the first number (50), so the display shows 40.
Can I use my keyboard to type numbers instead of clicking?
This calculator is driven by its on-screen buttons; the display is read-only and set to no keyboard input. You enter values by tapping or clicking the keypad rather than typing on a physical keyboard.
Why does my long decimal answer look shortened or rounded?
Results are rounded to 12 significant digits, so figures with many decimal places or repeating decimals are trimmed to fit that precision. This avoids floating-point noise but means the shown value can be a rounded approximation.
How do I make a number negative on the calculator?
Enter the number, then press the +/- key to flip its sign. Pressing it again switches the sign back, and it has no effect on a zero or an Error display.
Is there a memory or history feature to recall past results?
No. The calculator keeps only the current running calculation and does not store a history, memory register, or previous answers. Clearing with C resets everything, so record any intermediate numbers you want to keep.
What is the difference between C and the +/- buttons?
C clears the entire calculation, resetting the display to 0 and discarding any pending operator. The +/- button only toggles the sign of the number currently shown without clearing anything.
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