Online calculator
Click the keys or type on your keyboard. Memory, percent and a short history are built in.
Free · no signup Runs in your browser
How do I use this online calculator?
Click the keys, or type on your keyboard: the number keys, + - * / for the four operations, Enter or = for the result, Backspace to delete a digit and Escape to clear everything. The % key works like a pocket calculator: 200 + 10% gives 220, and 50 × 10% gives 5. M+ and M− add to or subtract from memory, MR recalls it and MC clears it. The last eight results appear below the keys, and you can click one to reuse it.
How it behaves
This is a standard 'immediate execution' calculator, like the one on a desk or in a phone. Each operation is carried out as soon as you press the next operator, working from left to right, so 2 + 3 × 4 is worked as (2 + 3) × 4 = 20, not 14. If you want the usual order of operations, where multiplication comes first, use the scientific calculator, which reads a whole expression and follows the rules.
Pressing = twice repeats the last operation: 5 + 2 = gives 7, and = again gives 9, then 11. That is handy for adding a constant repeatedly or for compound growth with the × key. The percent key changes with the operation in front of it. After + or −, it means a percentage of the first number, so 200 − 15% is 200 − 30 = 170, which is how you take a discount. After × or ÷, it simply divides by 100, so 80 × 25% is 20. On its own it divides the number by 100.
Results are rounded to 12 significant digits. Computers store most decimals in binary, so 0.1 + 0.2 is really 0.30000000000000004; rounding hides that noise so you see 0.3, as you would on paper.
It runs in your browser. Nothing you enter is sent anywhere or stored, and there is no sign-up.
Everyday uses
The calculator is meant for quick sums: adding a bill, working out change, splitting a total, checking a receipt, converting a percentage. For specific jobs there are dedicated tools with the right formulas, such as the tip calculator, the sale price calculator, the percentage calculator and the fraction calculator. Division by zero shows a clear message instead of a wrong answer, and very large or very small results switch to exponent form such as 1.5e20.
When to use it
- Quick everyday arithmetic and checking a bill or receipt
- Working out a discount or a tax with the % key
- Keeping a running total with the memory keys
- Doing a sum on a computer without opening another program
Mistakes it helps you avoid
- Expecting multiplication to come before addition on a left-to-right calculator.
- Using % without knowing what it is applied to.
- Trusting a calculator that shows floating-point noise such as 0.30000000000000004.
- Forgetting that = repeats the last operation.
The formula
How the answer is worked out.
a + b, a − b, a × b, a ÷ b are worked as soon as the next operator or = is pressed, from left to righta + b% = a + a × b ÷ 100; a − b% = a − a × b ÷ 100; a × b% = a × b ÷ 100pressing = again repeats the last operation with the same second numberresults are rounded to 12 significant digits
Numbers up to 15 digits can be typed. Dividing by zero shows a message. Because the calculator works step by step, use the scientific calculator when you need the order of operations or brackets.
Example: a 15% discount
A jacket costs $84.00 and is 15% off.
- Press84 − 15 % =
- After %15% of 84 = 12.6
- After =84 − 12.6 = 71.4
$71.40
Press × 1.13 = to add 13% HST in Ontario: $80.68.
Terms on this page
- Immediate execution
- A calculator that does each operation as soon as the next operator is pressed.
- Memory
- A stored number you can add to, subtract from and recall.
Common questions
Why does 2 + 3 × 4 give 20 here?
This calculator works left to right as you press the keys. The scientific calculator follows the order of operations and gives 14.
How does the percent key work?
After + or −, it takes that percentage of the first number; after × or ÷ it divides by 100.
How do I use the memory?
M+ adds the displayed number to memory, M− subtracts it, MR recalls it and MC clears it.
Can I use my keyboard?
Yes: numbers, + - * /, Enter, Backspace and Escape.
Is anything I calculate stored?
No. The history lives on the page only.
Is anything I enter sent to a server?
No. The calculation happens in your browser and nothing you type leaves your device.
Where these numbers come from
- Wikipedia — Calculator How the pocket calculator works and its history.
- Wikipedia — Floating-point arithmetic Why 0.1 + 0.2 is not exactly 0.3 in computers.
- Wikipedia — Percentage What a percentage is and how to work with it.
Last verified 2026-10-25 The method on this page is checked against the sources above at least once a year. Spotted something out of date? Tell us and we will fix it.
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