What is Basic Calculator?

The Basic Calculator is a free, standard arithmetic calculator for quick math operations. It supports addition, subtraction, multiplication, division, and percentages — all calculations happen privately on your device with no data leaving it.

Beyond the four operations, the calculator includes a percent key (1500 → 1500% → 15), a sign toggle for negatives, square root, raise-to-a-power (xʸ), a one-tap pi constant, full memory functions (M+, M−, MR, MC), copy-result-to-clipboard, and a rounding-mode badge that locks the display to two decimals or whole numbers when you're working with money or counts. A 20-entry history is saved in this device's local storage and survives a reload. The keyboard works too — type digits, +, -, *, /, ^ for power, p for pi, Enter for equals, and Backspace to delete.

How to use

1. Click the number buttons or use your keyboard to enter values
2. Select an operation like +, -, x, or / between numbers
3. Press = or Enter to see the result; tap AC to clear everything, or CE to fix just the last number

When to use

• Splitting a restaurant bill, calculating tax, or applying a 15% tip on the fly.
• Sanity-checking a spreadsheet figure without leaving the page.
• Walking a child through math homework with each calculation saved in the visible history.

Result

Calculate a 15% tip on a $45 meal: enter 45, tap x, enter 0.15, tap = to get $6.75.

FAQ

Why does the calculator show 0.1 + 0.2 = 0.3 instead of 0.30000000000000004?

JavaScript's underlying double-precision math really does return that long tail, but the calculator rounds results to 12 significant figures before display. That smooths over most binary-floating-point quirks while keeping enough precision for everyday arithmetic.

How does the percent key work exactly?

Pressing % divides the current display by 100. So 45, then x, then 15, then % gives 6.75, which is 15% of 45. For a tip plus the original bill, do 45, then +, then 15, then %, then = to get 51.75 (the 45 plus 15% of 45).

Why does the display show Error?

Two things trigger it: dividing by zero, or producing a number larger than what fits in floating point (about 1.8 × 10^308). Press AC to clear and start fresh, or CE to retype just the last entry. The history isn't affected, so you can still scroll back to previous valid calculations.

Will my calculation history survive a page refresh?

Yes. The most recent 20 results stay in this device's local storage, so refreshing the page or closing the tab and coming back later keeps everything. Clearing this site's saved data wipes the history, and private/incognito windows don't persist between sessions.

Can I do calculations like square root, powers, or pi?

Yes for those three. Tap √ for square root, xʸ for raise-to-a-power (try 2 xʸ 8 = 256), and π to insert 3.14159265358979 with one tap. Trigonometry (sin, cos) and logarithms (log, ln) are not here — for those, use a scientific calculator with the dedicated function keys plus parentheses for order of operations.

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