Basic Calculator
A simple calculator supporting addition, subtraction, multiplication, division, percent, and sign change. You can enter values with buttons or the keyboard.
How to use
- Enter an expression with numbers, operators, and parentheses. Multiplication and division are calculated first.
- Press "=" to show the result. The keyboard Enter also calculates.
- Use "C" to reset, or select a history item to reuse that expression.
Frequently asked questions
Can I use the keyboard?
Yes. You can use the number keys and +, -, *, /, plus Enter (calculate), Backspace (delete), and Esc (reset).
Does it have scientific functions?
This is a basic calculator focused on arithmetic, percent, and sign change.
How is % calculated?
It divides the currently shown value by 100. For example, pressing % after 50 gives 0.5.
Practical example and verification criteria
Basic Calculator: First distinguish whether you need calculation, recording, timing, audio, or a screen check, then set units, intervals, repetitions, volume, and storage options for the real environment. Locally saved data may exist only in the current browser and device and can disappear when browser data is cleared, private mode is used, or the device changes.
Basic Calculator: For a quick check, start with 2 + 3 × 4 → 14 as a small input whose result relationship you can verify directly. Confirm that the input summary, units, and options match your intent before applying the tool to real values or a copy of the source; this reduces setup mistakes.
Basic Calculator: Before relying on a timer or alert, test sound, volume, screen lock, and background behavior over a short interval, and also register important schedules in an operating-system alarm. Reopen exported files to verify saved results. Audio and screen results depend on hearing, ambient light, and device settings and do not replace professional measurement or long-term storage.
Basic Calculator · Work record: For real work, record the input conditions, selected options, and result together. Do not assume the same state will remain after a refresh or device change. Preserve important results separately using copy, download, a screenshot, or another method the page supports, then reopen them in the target environment.
Basic Calculator · Error check: If an error or unexpected result appears, reduce the input, run again with default options, and then change one condition at a time. Recording error messages and boundary values helps distinguish format issues, unsupported cases, and browser resource limits, and prevents an empty result from being mistaken for success.
Basic Calculator · Scope of use: Check the page guidance for browser processing versus server lookup, storage location, and supported scope. Use sensitive source material or secrets only when strictly necessary. High-impact work such as legal, financial, or medical decisions or changes to an operational system requires current authoritative information and a separate verification process.